From 0d3a2afeb914b7a643d86972149e185d31c4a830 Mon Sep 17 00:00:00 2001 From: rain84 Date: Thu, 27 Jun 2024 16:59:04 +0300 Subject: [PATCH 01/17] feat: update ts solution to lc problem No.0347 --- .../0347.Top K Frequent Elements/README.md | 18 ++++++++---------- .../0347.Top K Frequent Elements/README_EN.md | 18 ++++++++---------- .../0347.Top K Frequent Elements/Solution.ts | 18 ++++++++---------- 3 files changed, 24 insertions(+), 30 deletions(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/README.md b/solution/0300-0399/0347.Top K Frequent Elements/README.md index b8421d7368cba..37dcdb46da446 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/README.md +++ b/solution/0300-0399/0347.Top K Frequent Elements/README.md @@ -159,17 +159,15 @@ func (h *hp) Pop() any { a := *h; v := a[len(a)-1]; *h = a[:len(a)-1]; ```ts function topKFrequent(nums: number[], k: number): number[] { - let hashMap = new Map(); - for (let num of nums) { - hashMap.set(num, (hashMap.get(num) || 0) + 1); - } - let list = [...hashMap]; - list.sort((a, b) => b[1] - a[1]); - let ans = []; - for (let i = 0; i < k; i++) { - ans.push(list[i][0]); + const cnt = new Map(); + for (const num of nums) { + cnt.set(num, (cnt.get(num) || 0) + 1); } - return ans; + + return [...cnt] + .sort((a, b) => b[1] - a[1]) + .splice(0, k) + .map(([x]) => x); } ``` diff --git a/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md b/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md index 11e80c6b8e2d5..9406a014f39e6 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md +++ b/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md @@ -147,17 +147,15 @@ func (h *hp) Pop() any { a := *h; v := a[len(a)-1]; *h = a[:len(a)-1]; ```ts function topKFrequent(nums: number[], k: number): number[] { - let hashMap = new Map(); - for (let num of nums) { - hashMap.set(num, (hashMap.get(num) || 0) + 1); - } - let list = [...hashMap]; - list.sort((a, b) => b[1] - a[1]); - let ans = []; - for (let i = 0; i < k; i++) { - ans.push(list[i][0]); + const cnt = new Map(); + for (const num of nums) { + cnt.set(num, (cnt.get(num) || 0) + 1); } - return ans; + + return [...cnt] + .sort((a, b) => b[1] - a[1]) + .splice(0, k) + .map(([x]) => x); } ``` diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution.ts b/solution/0300-0399/0347.Top K Frequent Elements/Solution.ts index 9f20a96a72ebf..7f23f2ce02071 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution.ts +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution.ts @@ -1,13 +1,11 @@ function topKFrequent(nums: number[], k: number): number[] { - let hashMap = new Map(); - for (let num of nums) { - hashMap.set(num, (hashMap.get(num) || 0) + 1); + const cnt = new Map(); + for (const num of nums) { + cnt.set(num, (cnt.get(num) || 0) + 1); } - let list = [...hashMap]; - list.sort((a, b) => b[1] - a[1]); - let ans = []; - for (let i = 0; i < k; i++) { - ans.push(list[i][0]); - } - return ans; + + return [...cnt] + .sort((a, b) => b[1] - a[1]) + .splice(0, k) + .map(([x]) => x); } From a93628a712e1813ad5b7218b0d73c8ec28fe7742 Mon Sep 17 00:00:00 2001 From: rain84 Date: Thu, 27 Jun 2024 17:00:15 +0300 Subject: [PATCH 02/17] feat: add 3rd ts solution to lc problem: No.0347 --- .../0347.Top K Frequent Elements/README.md | 35 +++++++++++++++++++ .../0347.Top K Frequent Elements/README_EN.md | 35 +++++++++++++++++++ .../0347.Top K Frequent Elements/Solution3.ts | 20 +++++++++++ 3 files changed, 90 insertions(+) create mode 100644 solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts diff --git a/solution/0300-0399/0347.Top K Frequent Elements/README.md b/solution/0300-0399/0347.Top K Frequent Elements/README.md index 37dcdb46da446..605dfcf55cbe8 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/README.md +++ b/solution/0300-0399/0347.Top K Frequent Elements/README.md @@ -282,4 +282,39 @@ function topKFrequent(nums: number[], k: number): number[] { + + +### Solution 3. Priority queue + + + +#### TypeScript + +```ts +function topKFrequent(nums: number[], k: number): number[] { + const ans = Array(k); + const cnt = new Map(); + const minPQ = new MinPriorityQueue(); + + for (const x of nums) { + cnt.set(x, (cnt.get(x) ?? 0) + 1); + } + + for (const [x, c] of cnt) { + minPQ.enqueue(x, c); + if (minPQ.size() > k) minPQ.dequeue(); + } + + while (k--) { + ans[k] = minPQ.dequeue().element; + } + + return ans; +} +``` + + + + + diff --git a/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md b/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md index 9406a014f39e6..0c194259acc83 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md +++ b/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md @@ -270,4 +270,39 @@ function topKFrequent(nums: number[], k: number): number[] { + + +### Solution 3. Priority queue + + + +#### TypeScript + +```ts +function topKFrequent(nums: number[], k: number): number[] { + const ans = Array(k); + const cnt = new Map(); + const minPQ = new MinPriorityQueue(); + + for (const x of nums) { + cnt.set(x, (cnt.get(x) ?? 0) + 1); + } + + for (const [x, c] of cnt) { + minPQ.enqueue(x, c); + if (minPQ.size() > k) minPQ.dequeue(); + } + + while (k--) { + ans[k] = minPQ.dequeue().element; + } + + return ans; +} +``` + + + + + diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts b/solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts new file mode 100644 index 0000000000000..7cb05245e8988 --- /dev/null +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts @@ -0,0 +1,20 @@ +function topKFrequent(nums: number[], k: number): number[] { + const ans = Array(k); + const cnt = new Map(); + const minPQ = new MinPriorityQueue(); + + for (const x of nums) { + cnt.set(x, (cnt.get(x) ?? 0) + 1); + } + + for (const [x, c] of cnt) { + minPQ.enqueue(x, c); + if (minPQ.size() > k) minPQ.dequeue(); + } + + while (k--) { + ans[k] = minPQ.dequeue().element; + } + + return ans; +} From 3fa3fc1af0276f602440e77632cddbde44cb5e30 Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:02:19 +0800 Subject: [PATCH 03/17] Update README.md --- .../0347.Top K Frequent Elements/README.md | 224 +++++------------- 1 file changed, 58 insertions(+), 166 deletions(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/README.md b/solution/0300-0399/0347.Top K Frequent Elements/README.md index 605dfcf55cbe8..06706144b1a7f 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/README.md +++ b/solution/0300-0399/0347.Top K Frequent Elements/README.md @@ -62,9 +62,13 @@ tags: ### 方法一：哈希表 + 优先队列（小根堆） -使用哈希表统计每个元素出现的次数，然后使用优先队列（小根堆）维护前 $k$ 个出现次数最多的元素。 +我们可以使用一个哈希表 $\text{cnt}$ 统计每个元素出现的次数，然后使用一个小根堆（优先队列）来保存前 $k$ 个高频元素。 -时间复杂度 $O(n\log k)$。 +我们首先遍历一遍数组，统计每个元素出现的次数，然后遍历哈希表，将元素和出现次数存入小根堆中。如果小根堆的大小超过了 $k$，我们就将堆顶元素弹出，保证堆的大小始终为 $k$。 + +最后，我们将小根堆中的元素依次弹出，放入结果数组中即可。 + +时间复杂度 $O(n \times \log k)$，空间复杂度 $O(k)$。其中 $n$ 是数组的长度。 @@ -74,7 +78,7 @@ tags: class Solution: def topKFrequent(self, nums: List[int], k: int) -> List[int]: cnt = Counter(nums) - return [v[0] for v in cnt.most_common(k)] + return [x for x, _ in cnt.most_common(k)] ``` #### Java @@ -82,16 +86,18 @@ class Solution: ```java class Solution { public int[] topKFrequent(int[] nums, int k) { - Map frequency = Arrays.stream(nums).boxed().collect( - Collectors.groupingBy(Function.identity(), Collectors.counting())); - Queue> queue = new PriorityQueue<>(Map.Entry.comparingByValue()); - for (var entry : frequency.entrySet()) { - queue.offer(entry); - if (queue.size() > k) { - queue.poll(); + Map cnt = new HashMap<>(); + for (int x : nums) { + cnt.merge(x, 1, Integer::sum); + } + PriorityQueue> pq = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); + for (var e : cnt.entrySet()) { + pq.offer(e); + if (pq.size() > k) { + pq.poll(); } } - return queue.stream().mapToInt(Map.Entry::getKey).toArray(); + return pq.stream().mapToInt(Map.Entry::getKey).toArray(); } } ``` @@ -99,23 +105,24 @@ class Solution { #### C++ ```cpp -using pii = pair; - class Solution { public: vector topKFrequent(vector& nums, int k) { unordered_map cnt; - for (int v : nums) ++cnt[v]; + using pii = pair; + for (int x : nums) { + ++cnt[x]; + } priority_queue, greater> pq; - for (auto& [num, freq] : cnt) { - pq.push({freq, num}); + for (auto& [x, c] : cnt) { + pq.push({c, x}); if (pq.size() > k) { pq.pop(); } } - vector ans(k); - for (int i = 0; i < k; ++i) { - ans[i] = pq.top().second; + vector ans; + while (!pq.empty()) { + ans.push_back(pq.top().second); pq.pop(); } return ans; @@ -128,19 +135,19 @@ public: ```go func topKFrequent(nums []int, k int) []int { cnt := map[int]int{} - for _, v := range nums { - cnt[v]++ + for _, x := range nums { + cnt[x]++ } - h := hp{} - for v, freq := range cnt { - heap.Push(&h, pair{v, freq}) - if len(h) > k { - heap.Pop(&h) + pq := hp{} + for x, c := range cnt { + heap.Push(&pq, pair{x, c}) + if pq.Len() > k { + heap.Pop(&pq) } } ans := make([]int, k) - for i := range ans { - ans[i] = heap.Pop(&h).(pair).v + for i := 0; i < k; i++ { + ans[i] = heap.Pop(&pq).(pair).v } return ans } @@ -159,157 +166,42 @@ func (h *hp) Pop() any { a := *h; v := a[len(a)-1]; *h = a[:len(a)-1]; ```ts function topKFrequent(nums: number[], k: number): number[] { - const cnt = new Map(); - for (const num of nums) { - cnt.set(num, (cnt.get(num) || 0) + 1); + const cnt = new Map(); + for (const x of nums) { + cnt.set(x, (cnt.get(x) ?? 0) + 1); } - - return [...cnt] - .sort((a, b) => b[1] - a[1]) - .splice(0, k) - .map(([x]) => x); + const pq = new MinPriorityQueue(); + for (const [x, c] of cnt) { + pq.enqueue(x, c); + if (pq.size() > k) { + pq.dequeue(); + } + } + return pq.toArray().map(x => x.element); } ``` #### Rust ```rust -use std::collections::HashMap; +use std::cmp::Reverse; +use std::collections::{BinaryHeap, HashMap}; + impl Solution { pub fn top_k_frequent(nums: Vec, k: i32) -> Vec { - let mut map = HashMap::new(); - let mut max_count = 0; - for &num in nums.iter() { - let val = map.get(&num).unwrap_or(&0) + 1; - map.insert(num, val); - max_count = max_count.max(val); - } - let mut k = k as usize; - let mut res = vec![0; k]; - while k > 0 { - let mut next = 0; - for key in map.keys() { - let val = map[key]; - if val == max_count { - res[k - 1] = *key; - k -= 1; - } else if val < max_count { - next = next.max(val); - } - } - max_count = next; - } - res - } -} -``` - - - - - - - -### 方法二 - - - -#### Python3 - -```python -class Solution: - def topKFrequent(self, nums: List[int], k: int) -> List[int]: - cnt = Counter(nums) - hp = [] - for num, freq in cnt.items(): - heappush(hp, (freq, num)) - if len(hp) > k: - heappop(hp) - return [v[1] for v in hp] -``` - -#### Java - -```java -class Solution { - public int[] topKFrequent(int[] nums, int k) { - Map cnt = new HashMap<>(); - for (int v : nums) { - cnt.put(v, cnt.getOrDefault(v, 0) + 1); - } - PriorityQueue pq = new PriorityQueue<>((a, b) -> a[1] - b[1]); - for (var e : cnt.entrySet()) { - pq.offer(new int[] {e.getKey(), e.getValue()}); - if (pq.size() > k) { - pq.poll(); - } + let mut cnt = HashMap::new(); + for x in nums { + *cnt.entry(x).or_insert(0) += 1; } - int[] ans = new int[k]; - for (int i = 0; i < k; ++i) { - ans[i] = pq.poll()[0]; - } - return ans; - } -} -``` - -#### TypeScript - -```ts -function topKFrequent(nums: number[], k: number): number[] { - const map = new Map(); - let maxCount = 0; - for (const num of nums) { - map.set(num, (map.get(num) ?? 0) + 1); - maxCount = Math.max(maxCount, map.get(num)); - } - - const res = []; - while (k > 0) { - for (const key of map.keys()) { - if (map.get(key) === maxCount) { - res.push(key); - k--; + let mut pq = BinaryHeap::with_capacity(k as usize); + for (&x, &c) in cnt.iter() { + pq.push(Reverse((c, x))); + if pq.len() > k as usize { + pq.pop(); } } - maxCount--; - } - return res; -} -``` - - - - - - - -### Solution 3. Priority queue - - - -#### TypeScript - -```ts -function topKFrequent(nums: number[], k: number): number[] { - const ans = Array(k); - const cnt = new Map(); - const minPQ = new MinPriorityQueue(); - - for (const x of nums) { - cnt.set(x, (cnt.get(x) ?? 0) + 1); + pq.into_iter().map(|Reverse((_, x))| x).collect() } - - for (const [x, c] of cnt) { - minPQ.enqueue(x, c); - if (minPQ.size() > k) minPQ.dequeue(); - } - - while (k--) { - ans[k] = minPQ.dequeue().element; - } - - return ans; } ``` From 9c395cd361801fa12ca32e45e737a6b635b0b42d Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:02:37 +0800 Subject: [PATCH 04/17] Update README_EN.md --- .../0347.Top K Frequent Elements/README_EN.md | 226 +++++------------- 1 file changed, 61 insertions(+), 165 deletions(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md b/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md index 0c194259acc83..af8fa37b8f972 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md +++ b/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md @@ -52,7 +52,15 @@ tags: -### Solution 1 +### Solution 1: Hash Table + Priority Queue (Min Heap) + +We can use a hash table $\text{cnt}$ to count the occurrence of each element, and then use a min heap (priority queue) to store the top $k$ frequent elements. + +First, we traverse the array once to count the occurrence of each element. Then, we iterate through the hash table, storing each element and its count into the min heap. If the size of the min heap exceeds $k$, we pop the top element of the heap to ensure the heap size is always $k$. + +Finally, we pop the elements from the min heap one by one and place them into the result array. + +The time complexity is $O(n \log k)$, and the space complexity is $O(k)$. Here, $n$ is the length of the array. @@ -62,7 +70,7 @@ tags: class Solution: def topKFrequent(self, nums: List[int], k: int) -> List[int]: cnt = Counter(nums) - return [v[0] for v in cnt.most_common(k)] + return [x for x, _ in cnt.most_common(k)] ``` #### Java @@ -70,16 +78,18 @@ class Solution: ```java class Solution { public int[] topKFrequent(int[] nums, int k) { - Map frequency = Arrays.stream(nums).boxed().collect( - Collectors.groupingBy(Function.identity(), Collectors.counting())); - Queue> queue = new PriorityQueue<>(Map.Entry.comparingByValue()); - for (var entry : frequency.entrySet()) { - queue.offer(entry); - if (queue.size() > k) { - queue.poll(); + Map cnt = new HashMap<>(); + for (int x : nums) { + cnt.merge(x, 1, Integer::sum); + } + PriorityQueue> pq = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); + for (var e : cnt.entrySet()) { + pq.offer(e); + if (pq.size() > k) { + pq.poll(); } } - return queue.stream().mapToInt(Map.Entry::getKey).toArray(); + return pq.stream().mapToInt(Map.Entry::getKey).toArray(); } } ``` @@ -87,23 +97,24 @@ class Solution { #### C++ ```cpp -using pii = pair; - class Solution { public: vector topKFrequent(vector& nums, int k) { unordered_map cnt; - for (int v : nums) ++cnt[v]; + using pii = pair; + for (int x : nums) { + ++cnt[x]; + } priority_queue, greater> pq; - for (auto& [num, freq] : cnt) { - pq.push({freq, num}); + for (auto& [x, c] : cnt) { + pq.push({c, x}); if (pq.size() > k) { pq.pop(); } } - vector ans(k); - for (int i = 0; i < k; ++i) { - ans[i] = pq.top().second; + vector ans; + while (!pq.empty()) { + ans.push_back(pq.top().second); pq.pop(); } return ans; @@ -116,19 +127,19 @@ public: ```go func topKFrequent(nums []int, k int) []int { cnt := map[int]int{} - for _, v := range nums { - cnt[v]++ + for _, x := range nums { + cnt[x]++ } - h := hp{} - for v, freq := range cnt { - heap.Push(&h, pair{v, freq}) - if len(h) > k { - heap.Pop(&h) + pq := hp{} + for x, c := range cnt { + heap.Push(&pq, pair{x, c}) + if pq.Len() > k { + heap.Pop(&pq) } } ans := make([]int, k) - for i := range ans { - ans[i] = heap.Pop(&h).(pair).v + for i := 0; i < k; i++ { + ans[i] = heap.Pop(&pq).(pair).v } return ans } @@ -147,157 +158,42 @@ func (h *hp) Pop() any { a := *h; v := a[len(a)-1]; *h = a[:len(a)-1]; ```ts function topKFrequent(nums: number[], k: number): number[] { - const cnt = new Map(); - for (const num of nums) { - cnt.set(num, (cnt.get(num) || 0) + 1); + const cnt = new Map(); + for (const x of nums) { + cnt.set(x, (cnt.get(x) ?? 0) + 1); } - - return [...cnt] - .sort((a, b) => b[1] - a[1]) - .splice(0, k) - .map(([x]) => x); + const pq = new MinPriorityQueue(); + for (const [x, c] of cnt) { + pq.enqueue(x, c); + if (pq.size() > k) { + pq.dequeue(); + } + } + return pq.toArray().map(x => x.element); } ``` #### Rust ```rust -use std::collections::HashMap; +use std::cmp::Reverse; +use std::collections::{BinaryHeap, HashMap}; + impl Solution { pub fn top_k_frequent(nums: Vec, k: i32) -> Vec { - let mut map = HashMap::new(); - let mut max_count = 0; - for &num in nums.iter() { - let val = map.get(&num).unwrap_or(&0) + 1; - map.insert(num, val); - max_count = max_count.max(val); - } - let mut k = k as usize; - let mut res = vec![0; k]; - while k > 0 { - let mut next = 0; - for key in map.keys() { - let val = map[key]; - if val == max_count { - res[k - 1] = *key; - k -= 1; - } else if val < max_count { - next = next.max(val); - } - } - max_count = next; - } - res - } -} -``` - - - - - - - -### Solution 2 - - - -#### Python3 - -```python -class Solution: - def topKFrequent(self, nums: List[int], k: int) -> List[int]: - cnt = Counter(nums) - hp = [] - for num, freq in cnt.items(): - heappush(hp, (freq, num)) - if len(hp) > k: - heappop(hp) - return [v[1] for v in hp] -``` - -#### Java - -```java -class Solution { - public int[] topKFrequent(int[] nums, int k) { - Map cnt = new HashMap<>(); - for (int v : nums) { - cnt.put(v, cnt.getOrDefault(v, 0) + 1); - } - PriorityQueue pq = new PriorityQueue<>((a, b) -> a[1] - b[1]); - for (var e : cnt.entrySet()) { - pq.offer(new int[] {e.getKey(), e.getValue()}); - if (pq.size() > k) { - pq.poll(); - } - } - int[] ans = new int[k]; - for (int i = 0; i < k; ++i) { - ans[i] = pq.poll()[0]; + let mut cnt = HashMap::new(); + for x in nums { + *cnt.entry(x).or_insert(0) += 1; } - return ans; - } -} -``` - -#### TypeScript - -```ts -function topKFrequent(nums: number[], k: number): number[] { - const map = new Map(); - let maxCount = 0; - for (const num of nums) { - map.set(num, (map.get(num) ?? 0) + 1); - maxCount = Math.max(maxCount, map.get(num)); - } - - const res = []; - while (k > 0) { - for (const key of map.keys()) { - if (map.get(key) === maxCount) { - res.push(key); - k--; + let mut pq = BinaryHeap::with_capacity(k as usize); + for (&x, &c) in cnt.iter() { + pq.push(Reverse((c, x))); + if pq.len() > k as usize { + pq.pop(); } } - maxCount--; + pq.into_iter().map(|Reverse((_, x))| x).collect() } - return res; -} -``` - - - - - - - -### Solution 3. Priority queue - - - -#### TypeScript - -```ts -function topKFrequent(nums: number[], k: number): number[] { - const ans = Array(k); - const cnt = new Map(); - const minPQ = new MinPriorityQueue(); - - for (const x of nums) { - cnt.set(x, (cnt.get(x) ?? 0) + 1); - } - - for (const [x, c] of cnt) { - minPQ.enqueue(x, c); - if (minPQ.size() > k) minPQ.dequeue(); - } - - while (k--) { - ans[k] = minPQ.dequeue().element; - } - - return ans; } ``` From d59316c50fed83542f1b949dcf4c9ddc6086d311 Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:02:51 +0800 Subject: [PATCH 05/17] Delete solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts --- .../0347.Top K Frequent Elements/Solution3.ts | 20 ------------------- 1 file changed, 20 deletions(-) delete mode 100644 solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts b/solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts deleted file mode 100644 index 7cb05245e8988..0000000000000 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution3.ts +++ /dev/null @@ -1,20 +0,0 @@ -function topKFrequent(nums: number[], k: number): number[] { - const ans = Array(k); - const cnt = new Map(); - const minPQ = new MinPriorityQueue(); - - for (const x of nums) { - cnt.set(x, (cnt.get(x) ?? 0) + 1); - } - - for (const [x, c] of cnt) { - minPQ.enqueue(x, c); - if (minPQ.size() > k) minPQ.dequeue(); - } - - while (k--) { - ans[k] = minPQ.dequeue().element; - } - - return ans; -} From 66aaa325c0f61f30fc0915774e0809be7e600055 Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:03:33 +0800 Subject: [PATCH 06/17] Delete solution/0300-0399/0347.Top K Frequent Elements/Solution2.java --- .../Solution2.java | 20 ------------------- 1 file changed, 20 deletions(-) delete mode 100644 solution/0300-0399/0347.Top K Frequent Elements/Solution2.java diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution2.java b/solution/0300-0399/0347.Top K Frequent Elements/Solution2.java deleted file mode 100644 index 50579ba0ce6b6..0000000000000 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution2.java +++ /dev/null @@ -1,20 +0,0 @@ -class Solution { - public int[] topKFrequent(int[] nums, int k) { - Map cnt = new HashMap<>(); - for (int v : nums) { - cnt.put(v, cnt.getOrDefault(v, 0) + 1); - } - PriorityQueue pq = new PriorityQueue<>((a, b) -> a[1] - b[1]); - for (var e : cnt.entrySet()) { - pq.offer(new int[] {e.getKey(), e.getValue()}); - if (pq.size() > k) { - pq.poll(); - } - } - int[] ans = new int[k]; - for (int i = 0; i < k; ++i) { - ans[i] = pq.poll()[0]; - } - return ans; - } -} \ No newline at end of file From a1dc5a8bdd608e438bb268991ca733f2709b50a2 Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:03:42 +0800 Subject: [PATCH 07/17] Delete solution/0300-0399/0347.Top K Frequent Elements/Solution2.ts --- .../0347.Top K Frequent Elements/Solution2.ts | 20 ------------------- 1 file changed, 20 deletions(-) delete mode 100644 solution/0300-0399/0347.Top K Frequent Elements/Solution2.ts diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution2.ts b/solution/0300-0399/0347.Top K Frequent Elements/Solution2.ts deleted file mode 100644 index 9001644391a42..0000000000000 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution2.ts +++ /dev/null @@ -1,20 +0,0 @@ -function topKFrequent(nums: number[], k: number): number[] { - const map = new Map(); - let maxCount = 0; - for (const num of nums) { - map.set(num, (map.get(num) ?? 0) + 1); - maxCount = Math.max(maxCount, map.get(num)); - } - - const res = []; - while (k > 0) { - for (const key of map.keys()) { - if (map.get(key) === maxCount) { - res.push(key); - k--; - } - } - maxCount--; - } - return res; -} From 98b9386872e1ce2b8666f1542f2b7e63926d2c9a Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:03:52 +0800 Subject: [PATCH 08/17] Delete solution/0300-0399/0347.Top K Frequent Elements/Solution2.py --- .../0300-0399/0347.Top K Frequent Elements/Solution2.py | 9 --------- 1 file changed, 9 deletions(-) delete mode 100644 solution/0300-0399/0347.Top K Frequent Elements/Solution2.py diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution2.py b/solution/0300-0399/0347.Top K Frequent Elements/Solution2.py deleted file mode 100644 index 37e7fac77f36d..0000000000000 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution2.py +++ /dev/null @@ -1,9 +0,0 @@ -class Solution: - def topKFrequent(self, nums: List[int], k: int) -> List[int]: - cnt = Counter(nums) - hp = [] - for num, freq in cnt.items(): - heappush(hp, (freq, num)) - if len(hp) > k: - heappop(hp) - return [v[1] for v in hp] From 1b22daf5fc6367df1ba083d10c556c55d9d351fb Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:04:04 +0800 Subject: [PATCH 09/17] Update Solution.py --- solution/0300-0399/0347.Top K Frequent Elements/Solution.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution.py b/solution/0300-0399/0347.Top K Frequent Elements/Solution.py index bb2e27754c5f0..2f1eac588f73c 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution.py +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution.py @@ -1,4 +1,4 @@ class Solution: def topKFrequent(self, nums: List[int], k: int) -> List[int]: cnt = Counter(nums) - return [v[0] for v in cnt.most_common(k)] + return [x for x, _ in cnt.most_common(k)] From ddd8672fb4973d1baeac9cab378f915782a35cfa Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:04:12 +0800 Subject: [PATCH 10/17] Update Solution.java --- .../Solution.java | 20 ++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution.java b/solution/0300-0399/0347.Top K Frequent Elements/Solution.java index 2dd78e1c6fdbc..854760e2651ab 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution.java +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution.java @@ -1,14 +1,16 @@ class Solution { public int[] topKFrequent(int[] nums, int k) { - Map frequency = Arrays.stream(nums).boxed().collect( - Collectors.groupingBy(Function.identity(), Collectors.counting())); - Queue> queue = new PriorityQueue<>(Map.Entry.comparingByValue()); - for (var entry : frequency.entrySet()) { - queue.offer(entry); - if (queue.size() > k) { - queue.poll(); + Map cnt = new HashMap<>(); + for (int x : nums) { + cnt.merge(x, 1, Integer::sum); + } + PriorityQueue> pq = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); + for (var e : cnt.entrySet()) { + pq.offer(e); + if (pq.size() > k) { + pq.poll(); } } - return queue.stream().mapToInt(Map.Entry::getKey).toArray(); + return pq.stream().mapToInt(Map.Entry::getKey).toArray(); } -} \ No newline at end of file +} From 4848a04112fd95c5138a7456f86e15fed741ee22 Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:04:22 +0800 Subject: [PATCH 11/17] Update Solution.cpp --- .../0347.Top K Frequent Elements/Solution.cpp | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution.cpp b/solution/0300-0399/0347.Top K Frequent Elements/Solution.cpp index 6c9ddd0f1f3e6..dd6b67bdee2aa 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution.cpp +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution.cpp @@ -1,22 +1,23 @@ -using pii = pair; - class Solution { public: vector topKFrequent(vector& nums, int k) { unordered_map cnt; - for (int v : nums) ++cnt[v]; + using pii = pair; + for (int x : nums) { + ++cnt[x]; + } priority_queue, greater> pq; - for (auto& [num, freq] : cnt) { - pq.push({freq, num}); + for (auto& [x, c] : cnt) { + pq.push({c, x}); if (pq.size() > k) { pq.pop(); } } - vector ans(k); - for (int i = 0; i < k; ++i) { - ans[i] = pq.top().second; + vector ans; + while (!pq.empty()) { + ans.push_back(pq.top().second); pq.pop(); } return ans; } -}; \ No newline at end of file +}; From 103873e85418e7c25ef037029d860f96e8f774ff Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:04:31 +0800 Subject: [PATCH 12/17] Update Solution.go --- .../0347.Top K Frequent Elements/Solution.go | 20 +++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution.go b/solution/0300-0399/0347.Top K Frequent Elements/Solution.go index 4df836e6d8670..7cf9043a523d3 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution.go +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution.go @@ -1,18 +1,18 @@ func topKFrequent(nums []int, k int) []int { cnt := map[int]int{} - for _, v := range nums { - cnt[v]++ + for _, x := range nums { + cnt[x]++ } - h := hp{} - for v, freq := range cnt { - heap.Push(&h, pair{v, freq}) - if len(h) > k { - heap.Pop(&h) + pq := hp{} + for x, c := range cnt { + heap.Push(&pq, pair{x, c}) + if pq.Len() > k { + heap.Pop(&pq) } } ans := make([]int, k) - for i := range ans { - ans[i] = heap.Pop(&h).(pair).v + for i := 0; i < k; i++ { + ans[i] = heap.Pop(&pq).(pair).v } return ans } @@ -24,4 +24,4 @@ func (h hp) Len() int { return len(h) } func (h hp) Less(i, j int) bool { return h[i].cnt < h[j].cnt } func (h hp) Swap(i, j int) { h[i], h[j] = h[j], h[i] } func (h *hp) Push(v any) { *h = append(*h, v.(pair)) } -func (h *hp) Pop() any { a := *h; v := a[len(a)-1]; *h = a[:len(a)-1]; return v } \ No newline at end of file +func (h *hp) Pop() any { a := *h; v := a[len(a)-1]; *h = a[:len(a)-1]; return v } From dedd6e5903a70390f204d7964365ae5e302be85c Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:04:41 +0800 Subject: [PATCH 13/17] Update Solution.ts --- .../0347.Top K Frequent Elements/Solution.ts | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution.ts b/solution/0300-0399/0347.Top K Frequent Elements/Solution.ts index 7f23f2ce02071..5b647b5a01d9c 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution.ts +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution.ts @@ -1,11 +1,14 @@ function topKFrequent(nums: number[], k: number): number[] { - const cnt = new Map(); - for (const num of nums) { - cnt.set(num, (cnt.get(num) || 0) + 1); + const cnt = new Map(); + for (const x of nums) { + cnt.set(x, (cnt.get(x) ?? 0) + 1); } - - return [...cnt] - .sort((a, b) => b[1] - a[1]) - .splice(0, k) - .map(([x]) => x); + const pq = new MinPriorityQueue(); + for (const [x, c] of cnt) { + pq.enqueue(x, c); + if (pq.size() > k) { + pq.dequeue(); + } + } + return pq.toArray().map(x => x.element); } From 2f57290af91f04991e2f2970408455ccaca38322 Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:04:50 +0800 Subject: [PATCH 14/17] Update Solution.rs --- .../0347.Top K Frequent Elements/Solution.rs | 33 +++++++------------ 1 file changed, 12 insertions(+), 21 deletions(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution.rs b/solution/0300-0399/0347.Top K Frequent Elements/Solution.rs index 1de7f5007bb07..9bed087c179ec 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution.rs +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution.rs @@ -1,28 +1,19 @@ -use std::collections::HashMap; +use std::cmp::Reverse; +use std::collections::{BinaryHeap, HashMap}; + impl Solution { pub fn top_k_frequent(nums: Vec, k: i32) -> Vec { - let mut map = HashMap::new(); - let mut max_count = 0; - for &num in nums.iter() { - let val = map.get(&num).unwrap_or(&0) + 1; - map.insert(num, val); - max_count = max_count.max(val); + let mut cnt = HashMap::new(); + for x in nums { + *cnt.entry(x).or_insert(0) += 1; } - let mut k = k as usize; - let mut res = vec![0; k]; - while k > 0 { - let mut next = 0; - for key in map.keys() { - let val = map[key]; - if val == max_count { - res[k - 1] = *key; - k -= 1; - } else if val < max_count { - next = next.max(val); - } + let mut pq = BinaryHeap::with_capacity(k as usize); + for (&x, &c) in cnt.iter() { + pq.push(Reverse((c, x))); + if pq.len() > k as usize { + pq.pop(); } - max_count = next; } - res + pq.into_iter().map(|Reverse((_, x))| x).collect() } } From 40e34a29485f7bf4d355b18aad198aa7caca8fea Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:06:21 +0800 Subject: [PATCH 15/17] Update Solution.java --- solution/0300-0399/0347.Top K Frequent Elements/Solution.java | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/Solution.java b/solution/0300-0399/0347.Top K Frequent Elements/Solution.java index 854760e2651ab..0161a90bf1e76 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/Solution.java +++ b/solution/0300-0399/0347.Top K Frequent Elements/Solution.java @@ -4,7 +4,8 @@ public int[] topKFrequent(int[] nums, int k) { for (int x : nums) { cnt.merge(x, 1, Integer::sum); } - PriorityQueue> pq = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); + PriorityQueue> pq + = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); for (var e : cnt.entrySet()) { pq.offer(e); if (pq.size() > k) { From 5fd646160c3f9e83005daf95153047f0572007a0 Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:06:33 +0800 Subject: [PATCH 16/17] Update README.md --- solution/0300-0399/0347.Top K Frequent Elements/README.md | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/README.md b/solution/0300-0399/0347.Top K Frequent Elements/README.md index 06706144b1a7f..0a21210a0545e 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/README.md +++ b/solution/0300-0399/0347.Top K Frequent Elements/README.md @@ -90,7 +90,8 @@ class Solution { for (int x : nums) { cnt.merge(x, 1, Integer::sum); } - PriorityQueue> pq = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); + PriorityQueue> pq + = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); for (var e : cnt.entrySet()) { pq.offer(e); if (pq.size() > k) { From caf65a88f3d1fcb8c8aa101094cbfebe44ca42ff Mon Sep 17 00:00:00 2001 From: Libin YANG Date: Fri, 28 Jun 2024 10:06:46 +0800 Subject: [PATCH 17/17] Update README_EN.md --- solution/0300-0399/0347.Top K Frequent Elements/README_EN.md | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md b/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md index af8fa37b8f972..c72b5148eb7d4 100644 --- a/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md +++ b/solution/0300-0399/0347.Top K Frequent Elements/README_EN.md @@ -82,7 +82,8 @@ class Solution { for (int x : nums) { cnt.merge(x, 1, Integer::sum); } - PriorityQueue> pq = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); + PriorityQueue> pq + = new PriorityQueue<>(Comparator.comparingInt(Map.Entry::getValue)); for (var e : cnt.entrySet()) { pq.offer(e); if (pq.size() > k) {