From 25b08b0de29d65fd2ba41fd1b68f86f394e6e26f Mon Sep 17 00:00:00 2001 From: yanglbme Date: Fri, 15 Sep 2023 15:04:15 +0800 Subject: [PATCH] feat: add solutions to lc problem: No.2192 No.2192.All Ancestors of a Node in a Directed Acyclic Graph --- .../README.md | 203 ++++++++++-------- .../README_EN.md | 197 +++++++++-------- .../Solution.cpp | 45 ++-- .../Solution.go | 36 ++-- .../Solution.java | 57 ++--- .../Solution.py | 32 ++- .../Solution.ts | 26 +++ 7 files changed, 327 insertions(+), 269 deletions(-) create mode 100644 solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.ts diff --git a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/README.md b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/README.md index e9566676591af..7e40cd101d7ae 100644 --- a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/README.md +++ b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/README.md @@ -67,6 +67,12 @@ **方法一：BFS** +我们先根据二维数组 $edges$ 构建邻接表 $g$，其中 $g[i]$ 表示节点 $i$ 的所有后继节点。 + +然后我们从小到大枚举节点 $i$ 作为祖先节点，使用 BFS 搜索节点 $i$ 的所有后继节点，把节点 $i$ 加入这些后继节点的祖先列表中。 + +时间复杂度 $O(n^2)$，空间复杂度 $O(n^2)$。其中 $n$ 是节点数。 + ### **Python3** @@ -76,27 +82,23 @@ ```python class Solution: def getAncestors(self, n: int, edges: List[List[int]]) -> List[List[int]]: + def bfs(s: int): + q = deque([s]) + vis = {s} + while q: + i = q.popleft() + for j in g[i]: + if j not in vis: + vis.add(j) + q.append(j) + ans[j].append(s) + g = defaultdict(list) for u, v in edges: - g[v].append(u) - ans = [] + g[u].append(v) + ans = [[] for _ in range(n)] for i in range(n): - if not g[i]: - ans.append([]) - continue - q = deque([i]) - vis = [False] * n - vis[i] = True - t = [] - while q: - for _ in range(len(q)): - v = q.popleft() - for u in g[v]: - if not vis[u]: - vis[u] = True - q.append(u) - t.append(u) - ans.append(sorted(t)) + bfs(i) return ans ``` @@ -106,39 +108,42 @@ class Solution: ```java class Solution { + private int n; + private List[] g; + private List> ans; + public List> getAncestors(int n, int[][] edges) { - List[] g = new List[n]; - Arrays.setAll(g, k -> new ArrayList<>()); - for (int[] e : edges) { - g[e[1]].add(e[0]); + g = new List[n]; + this.n = n; + Arrays.setAll(g, i -> new ArrayList<>()); + for (var e : edges) { + g[e[0]].add(e[1]); } - List> ans = new ArrayList<>(); + ans = new ArrayList<>(); for (int i = 0; i < n; ++i) { - List t = new ArrayList<>(); - if (g[i].isEmpty()) { - ans.add(t); - continue; - } - Deque q = new ArrayDeque<>(); - q.offer(i); - boolean[] vis = new boolean[n]; - vis[i] = true; - while (!q.isEmpty()) { - for (int j = q.size(); j > 0; --j) { - int v = q.poll(); - for (int u : g[v]) { - if (!vis[u]) { - vis[u] = true; - q.offer(u); - t.add(u); - } - } + ans.add(new ArrayList<>()); + } + for (int i = 0; i < n; ++i) { + bfs(i); + } + return ans; + } + + private void bfs(int s) { + Deque q = new ArrayDeque<>(); + q.offer(s); + boolean[] vis = new boolean[n]; + vis[s] = true; + while (!q.isEmpty()) { + int i = q.poll(); + for (int j : g[i]) { + if (!vis[j]) { + vis[j] = true; + q.offer(j); + ans.get(j).add(s); } } - Collections.sort(t); - ans.add(t); } - return ans; } } ``` @@ -149,32 +154,31 @@ class Solution { class Solution { public: vector> getAncestors(int n, vector>& edges) { - vector> g(n); - for (auto& e : edges) g[e[1]].push_back(e[0]); - vector> ans; - for (int i = 0; i < n; ++i) { - vector t; - if (g[i].empty()) { - ans.push_back(t); - continue; - } - queue q{{i}}; - vector vis(n); - vis[i] = true; - while (!q.empty()) { - for (int j = q.size(); j > 0; --j) { - int v = q.front(); - q.pop(); - for (int u : g[v]) { - if (vis[u]) continue; - vis[u] = true; - q.push(u); - t.push_back(u); + vector g[n]; + for (auto& e : edges) { + g[e[0]].push_back(e[1]); + } + vector> ans(n); + auto bfs = [&](int s) { + queue q; + q.push(s); + bool vis[n]; + memset(vis, 0, sizeof(vis)); + vis[s] = true; + while (q.size()) { + int i = q.front(); + q.pop(); + for (int j : g[i]) { + if (!vis[j]) { + vis[j] = true; + ans[j].push_back(s); + q.push(j); } } } - sort(t.begin(), t.end()); - ans.push_back(t); + }; + for (int i = 0; i < n; ++i) { + bfs(i); } return ans; } @@ -187,33 +191,27 @@ public: func getAncestors(n int, edges [][]int) [][]int { g := make([][]int, n) for _, e := range edges { - g[e[1]] = append(g[e[1]], e[0]) + g[e[0]] = append(g[e[0]], e[1]) } - var ans [][]int - for i := 0; i < n; i++ { - var t []int - if len(g[i]) == 0 { - ans = append(ans, t) - continue - } - q := []int{i} + ans := make([][]int, n) + bfs := func(s int) { + q := []int{s} vis := make([]bool, n) - vis[i] = true + vis[s] = true for len(q) > 0 { - for j := len(q); j > 0; j-- { - v := q[0] - q = q[1:] - for _, u := range g[v] { - if !vis[u] { - vis[u] = true - q = append(q, u) - t = append(t, u) - } + i := q[0] + q = q[1:] + for _, j := range g[i] { + if !vis[j] { + vis[j] = true + q = append(q, j) + ans[j] = append(ans[j], s) } } } - sort.Ints(t) - ans = append(ans, t) + } + for i := 0; i < n; i++ { + bfs(i) } return ans } @@ -222,7 +220,32 @@ func getAncestors(n int, edges [][]int) [][]int { ### **TypeScript** ```ts - +function getAncestors(n: number, edges: number[][]): number[][] { + const g: number[][] = Array.from({ length: n }, () => []); + for (const [u, v] of edges) { + g[u].push(v); + } + const ans: number[][] = Array.from({ length: n }, () => []); + const bfs = (s: number) => { + const q: number[] = [s]; + const vis: boolean[] = Array.from({ length: n }, () => false); + vis[s] = true; + while (q.length) { + const i = q.shift()!; + for (const j of g[i]) { + if (!vis[j]) { + vis[j] = true; + ans[j].push(s); + q.push(j); + } + } + } + }; + for (let i = 0; i < n; ++i) { + bfs(i); + } + return ans; +} ``` ### **...** diff --git a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/README_EN.md b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/README_EN.md index eb073a4e1abc7..883d37df8c10e 100644 --- a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/README_EN.md +++ b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/README_EN.md @@ -66,27 +66,23 @@ BFS. ```python class Solution: def getAncestors(self, n: int, edges: List[List[int]]) -> List[List[int]]: + def bfs(s: int): + q = deque([s]) + vis = {s} + while q: + i = q.popleft() + for j in g[i]: + if j not in vis: + vis.add(j) + q.append(j) + ans[j].append(s) + g = defaultdict(list) for u, v in edges: - g[v].append(u) - ans = [] + g[u].append(v) + ans = [[] for _ in range(n)] for i in range(n): - if not g[i]: - ans.append([]) - continue - q = deque([i]) - vis = [False] * n - vis[i] = True - t = [] - while q: - for _ in range(len(q)): - v = q.popleft() - for u in g[v]: - if not vis[u]: - vis[u] = True - q.append(u) - t.append(u) - ans.append(sorted(t)) + bfs(i) return ans ``` @@ -94,39 +90,42 @@ class Solution: ```java class Solution { + private int n; + private List[] g; + private List> ans; + public List> getAncestors(int n, int[][] edges) { - List[] g = new List[n]; - Arrays.setAll(g, k -> new ArrayList<>()); - for (int[] e : edges) { - g[e[1]].add(e[0]); + g = new List[n]; + this.n = n; + Arrays.setAll(g, i -> new ArrayList<>()); + for (var e : edges) { + g[e[0]].add(e[1]); } - List> ans = new ArrayList<>(); + ans = new ArrayList<>(); for (int i = 0; i < n; ++i) { - List t = new ArrayList<>(); - if (g[i].isEmpty()) { - ans.add(t); - continue; - } - Deque q = new ArrayDeque<>(); - q.offer(i); - boolean[] vis = new boolean[n]; - vis[i] = true; - while (!q.isEmpty()) { - for (int j = q.size(); j > 0; --j) { - int v = q.poll(); - for (int u : g[v]) { - if (!vis[u]) { - vis[u] = true; - q.offer(u); - t.add(u); - } - } + ans.add(new ArrayList<>()); + } + for (int i = 0; i < n; ++i) { + bfs(i); + } + return ans; + } + + private void bfs(int s) { + Deque q = new ArrayDeque<>(); + q.offer(s); + boolean[] vis = new boolean[n]; + vis[s] = true; + while (!q.isEmpty()) { + int i = q.poll(); + for (int j : g[i]) { + if (!vis[j]) { + vis[j] = true; + q.offer(j); + ans.get(j).add(s); } } - Collections.sort(t); - ans.add(t); } - return ans; } } ``` @@ -137,32 +136,31 @@ class Solution { class Solution { public: vector> getAncestors(int n, vector>& edges) { - vector> g(n); - for (auto& e : edges) g[e[1]].push_back(e[0]); - vector> ans; - for (int i = 0; i < n; ++i) { - vector t; - if (g[i].empty()) { - ans.push_back(t); - continue; - } - queue q{{i}}; - vector vis(n); - vis[i] = true; - while (!q.empty()) { - for (int j = q.size(); j > 0; --j) { - int v = q.front(); - q.pop(); - for (int u : g[v]) { - if (vis[u]) continue; - vis[u] = true; - q.push(u); - t.push_back(u); + vector g[n]; + for (auto& e : edges) { + g[e[0]].push_back(e[1]); + } + vector> ans(n); + auto bfs = [&](int s) { + queue q; + q.push(s); + bool vis[n]; + memset(vis, 0, sizeof(vis)); + vis[s] = true; + while (q.size()) { + int i = q.front(); + q.pop(); + for (int j : g[i]) { + if (!vis[j]) { + vis[j] = true; + ans[j].push_back(s); + q.push(j); } } } - sort(t.begin(), t.end()); - ans.push_back(t); + }; + for (int i = 0; i < n; ++i) { + bfs(i); } return ans; } @@ -175,33 +173,27 @@ public: func getAncestors(n int, edges [][]int) [][]int { g := make([][]int, n) for _, e := range edges { - g[e[1]] = append(g[e[1]], e[0]) + g[e[0]] = append(g[e[0]], e[1]) } - var ans [][]int - for i := 0; i < n; i++ { - var t []int - if len(g[i]) == 0 { - ans = append(ans, t) - continue - } - q := []int{i} + ans := make([][]int, n) + bfs := func(s int) { + q := []int{s} vis := make([]bool, n) - vis[i] = true + vis[s] = true for len(q) > 0 { - for j := len(q); j > 0; j-- { - v := q[0] - q = q[1:] - for _, u := range g[v] { - if !vis[u] { - vis[u] = true - q = append(q, u) - t = append(t, u) - } + i := q[0] + q = q[1:] + for _, j := range g[i] { + if !vis[j] { + vis[j] = true + q = append(q, j) + ans[j] = append(ans[j], s) } } } - sort.Ints(t) - ans = append(ans, t) + } + for i := 0; i < n; i++ { + bfs(i) } return ans } @@ -210,7 +202,32 @@ func getAncestors(n int, edges [][]int) [][]int { ### **TypeScript** ```ts - +function getAncestors(n: number, edges: number[][]): number[][] { + const g: number[][] = Array.from({ length: n }, () => []); + for (const [u, v] of edges) { + g[u].push(v); + } + const ans: number[][] = Array.from({ length: n }, () => []); + const bfs = (s: number) => { + const q: number[] = [s]; + const vis: boolean[] = Array.from({ length: n }, () => false); + vis[s] = true; + while (q.length) { + const i = q.shift()!; + for (const j of g[i]) { + if (!vis[j]) { + vis[j] = true; + ans[j].push(s); + q.push(j); + } + } + } + }; + for (let i = 0; i < n; ++i) { + bfs(i); + } + return ans; +} ``` ### **...** diff --git a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.cpp b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.cpp index 3261c345b0ee4..1b6e4faae9d17 100644 --- a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.cpp +++ b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.cpp @@ -1,32 +1,31 @@ class Solution { public: vector> getAncestors(int n, vector>& edges) { - vector> g(n); - for (auto& e : edges) g[e[1]].push_back(e[0]); - vector> ans; - for (int i = 0; i < n; ++i) { - vector t; - if (g[i].empty()) { - ans.push_back(t); - continue; - } - queue q{{i}}; - vector vis(n); - vis[i] = true; - while (!q.empty()) { - for (int j = q.size(); j > 0; --j) { - int v = q.front(); - q.pop(); - for (int u : g[v]) { - if (vis[u]) continue; - vis[u] = true; - q.push(u); - t.push_back(u); + vector g[n]; + for (auto& e : edges) { + g[e[0]].push_back(e[1]); + } + vector> ans(n); + auto bfs = [&](int s) { + queue q; + q.push(s); + bool vis[n]; + memset(vis, 0, sizeof(vis)); + vis[s] = true; + while (q.size()) { + int i = q.front(); + q.pop(); + for (int j : g[i]) { + if (!vis[j]) { + vis[j] = true; + ans[j].push_back(s); + q.push(j); } } } - sort(t.begin(), t.end()); - ans.push_back(t); + }; + for (int i = 0; i < n; ++i) { + bfs(i); } return ans; } diff --git a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.go b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.go index 3e0c13163d22b..27d60b24fdad5 100644 --- a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.go +++ b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.go @@ -1,33 +1,27 @@ func getAncestors(n int, edges [][]int) [][]int { g := make([][]int, n) for _, e := range edges { - g[e[1]] = append(g[e[1]], e[0]) + g[e[0]] = append(g[e[0]], e[1]) } - var ans [][]int - for i := 0; i < n; i++ { - var t []int - if len(g[i]) == 0 { - ans = append(ans, t) - continue - } - q := []int{i} + ans := make([][]int, n) + bfs := func(s int) { + q := []int{s} vis := make([]bool, n) - vis[i] = true + vis[s] = true for len(q) > 0 { - for j := len(q); j > 0; j-- { - v := q[0] - q = q[1:] - for _, u := range g[v] { - if !vis[u] { - vis[u] = true - q = append(q, u) - t = append(t, u) - } + i := q[0] + q = q[1:] + for _, j := range g[i] { + if !vis[j] { + vis[j] = true + q = append(q, j) + ans[j] = append(ans[j], s) } } } - sort.Ints(t) - ans = append(ans, t) + } + for i := 0; i < n; i++ { + bfs(i) } return ans } \ No newline at end of file diff --git a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.java b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.java index fb53d4cffdf3b..c380d79d2d2a2 100644 --- a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.java +++ b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.java @@ -1,36 +1,39 @@ class Solution { + private int n; + private List[] g; + private List> ans; + public List> getAncestors(int n, int[][] edges) { - List[] g = new List[n]; - Arrays.setAll(g, k -> new ArrayList<>()); - for (int[] e : edges) { - g[e[1]].add(e[0]); + g = new List[n]; + this.n = n; + Arrays.setAll(g, i -> new ArrayList<>()); + for (var e : edges) { + g[e[0]].add(e[1]); } - List> ans = new ArrayList<>(); + ans = new ArrayList<>(); for (int i = 0; i < n; ++i) { - List t = new ArrayList<>(); - if (g[i].isEmpty()) { - ans.add(t); - continue; - } - Deque q = new ArrayDeque<>(); - q.offer(i); - boolean[] vis = new boolean[n]; - vis[i] = true; - while (!q.isEmpty()) { - for (int j = q.size(); j > 0; --j) { - int v = q.poll(); - for (int u : g[v]) { - if (!vis[u]) { - vis[u] = true; - q.offer(u); - t.add(u); - } - } + ans.add(new ArrayList<>()); + } + for (int i = 0; i < n; ++i) { + bfs(i); + } + return ans; + } + + private void bfs(int s) { + Deque q = new ArrayDeque<>(); + q.offer(s); + boolean[] vis = new boolean[n]; + vis[s] = true; + while (!q.isEmpty()) { + int i = q.poll(); + for (int j : g[i]) { + if (!vis[j]) { + vis[j] = true; + q.offer(j); + ans.get(j).add(s); } } - Collections.sort(t); - ans.add(t); } - return ans; } } \ No newline at end of file diff --git a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.py b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.py index ce13490b87d46..f1f156f7468df 100644 --- a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.py +++ b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.py @@ -1,24 +1,20 @@ class Solution: def getAncestors(self, n: int, edges: List[List[int]]) -> List[List[int]]: + def bfs(s: int): + q = deque([s]) + vis = {s} + while q: + i = q.popleft() + for j in g[i]: + if j not in vis: + vis.add(j) + q.append(j) + ans[j].append(s) + g = defaultdict(list) for u, v in edges: - g[v].append(u) - ans = [] + g[u].append(v) + ans = [[] for _ in range(n)] for i in range(n): - if not g[i]: - ans.append([]) - continue - q = deque([i]) - vis = [False] * n - vis[i] = True - t = [] - while q: - for _ in range(len(q)): - v = q.popleft() - for u in g[v]: - if not vis[u]: - vis[u] = True - q.append(u) - t.append(u) - ans.append(sorted(t)) + bfs(i) return ans diff --git a/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.ts b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.ts new file mode 100644 index 0000000000000..55a7ff69c6fb6 --- /dev/null +++ b/solution/2100-2199/2192.All Ancestors of a Node in a Directed Acyclic Graph/Solution.ts @@ -0,0 +1,26 @@ +function getAncestors(n: number, edges: number[][]): number[][] { + const g: number[][] = Array.from({ length: n }, () => []); + for (const [u, v] of edges) { + g[u].push(v); + } + const ans: number[][] = Array.from({ length: n }, () => []); + const bfs = (s: number) => { + const q: number[] = [s]; + const vis: boolean[] = Array.from({ length: n }, () => false); + vis[s] = true; + while (q.length) { + const i = q.shift()!; + for (const j of g[i]) { + if (!vis[j]) { + vis[j] = true; + ans[j].push(s); + q.push(j); + } + } + } + }; + for (let i = 0; i < n; ++i) { + bfs(i); + } + return ans; +}