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yanglbmeyanglbme
committedAug 16, 2021
feat: add solutions to lc problem: No.1288.Remove Covered Intervals
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v0.2.0v0.1.7
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Diff for: ‎solution/1200-1299/1288.Remove Covered Intervals/README.md

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@@ -32,27 +32,100 @@
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<li>对于所有的&nbsp;<code>i != j</code>：<code>intervals[i] != intervals[j]</code></li>
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</ul>
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## 解法
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<!-- 这里可写通用的实现逻辑 -->
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对起点按升序排列，若起点相同，则对终点按降序排列。
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设 cnt 表示没有被覆盖的区间数，初始化为 1，pre 表示前一个未被覆盖的区间，初始化为 `intervals[0]`。
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从下标 1 开始遍历区间列表，若 `pre[1] < intervals[i][1]`，说明当前区间不被前一个区间覆盖，`cnt++`，并且更新 pre 为 `intervals[i]`。否则表示当前区间被前一个区间覆盖，不做任何操作。
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最后返回 cnt 即可。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def removeCoveredIntervals(self, intervals: List[List[int]]) -> int:
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intervals.sort(key=lambda x: (x[0], -x[1]))
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cnt, pre = 1, intervals[0]
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for e in intervals[1:]:
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if pre[1] < e[1]:
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cnt += 1
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pre = e
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return cnt
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public int removeCoveredIntervals(int[][] intervals) {
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Arrays.sort(intervals, (a, b) -> a[0] - b[0] == 0 ? b[1] - a[1] : a[0] - b[0]);
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int[] pre = intervals[0];
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int cnt = 1;
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for (int i = 1; i < intervals.length; ++i) {
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if (pre[1] < intervals[i][1]) {
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++cnt;
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pre = intervals[i];
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}
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}
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return cnt;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int removeCoveredIntervals(vector<vector<int>> &intervals) {
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sort(intervals.begin(), intervals.end(), [](const vector<int> &a, const vector<int> &b)
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{ return a[0] == b[0] ? b[1] < a[1] : a[0] < b[0]; });
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int cnt = 1;
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vector<int> pre = intervals[0];
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for (int i = 1; i < intervals.size(); ++i)
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{
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if (pre[1] < intervals[i][1])
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{
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++cnt;
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pre = intervals[i];
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}
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}
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return cnt;
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}
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};
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```
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### **Go**
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```go
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func removeCoveredIntervals(intervals [][]int) int {
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sort.Slice(intervals, func(i, j int) bool {
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if intervals[i][0] == intervals[j][0] {
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return intervals[j][1] < intervals[i][1]
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}
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return intervals[i][0] < intervals[j][0]
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})
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cnt := 1
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pre := intervals[0]
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for i := 1; i < len(intervals); i++ {
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if pre[1] < intervals[i][1] {
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cnt++
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pre = intervals[i]
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}
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}
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return cnt
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}
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```
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### **...**

Diff for: ‎solution/1200-1299/1288.Remove Covered Intervals/README_EN.md

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@@ -6,22 +6,14 @@
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<p>Given a list of <code>intervals</code>, remove all intervals that are covered by another interval in the list.</p>
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<p>Interval <code>[a,b)</code> is covered by&nbsp;interval <code>[c,d)</code> if and only if <code>c &lt;= a</code> and <code>b &lt;= d</code>.</p>
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<p>After doing so, return <em>the number of remaining intervals</em>.</p>
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<p>&nbsp;</p>
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<p><strong>Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> intervals = [[1,4],[3,6],[2,8]]
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</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> intervals = [[1,4],[2,3]]
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</pre>
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<p><strong>Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> intervals = [[0,10],[5,12]]
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</pre>
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<p><strong>Example 4:</strong></p>
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<pre>
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<strong>Input:</strong> intervals = [[3,10],[4,10],[5,11]]
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</pre>
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<p><strong>Example 5:</strong></p>
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<pre>
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<strong>Input:</strong> intervals = [[1,2],[1,4],[3,4]]
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</pre>
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<p>&nbsp;</p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>1 &lt;= intervals.length &lt;= 1000</code></li>
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<li><code>intervals[i].length == 2</code></li>
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## Solutions
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- Sort `intervals` by increasing of `startTime` and decreasing of `endTime`.
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- `cnt = 1`: `cnt` is the result.
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- `pre = intervals[0]`: `pre` is the last interval
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- For each `interval` in `intervals`
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- if `pre.endTime < interval.endTime`, means `interval` is not overlapped then we count `cnt`, and update `pre = interval`
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- else we do nothing
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- Return `cnt`
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<!-- tabs:start -->
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### **Python3**
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```python
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class Solution:
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def removeCoveredIntervals(self, intervals: List[List[int]]) -> int:
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intervals.sort(key=lambda x: (x[0], -x[1]))
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cnt, pre = 1, intervals[0]
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for e in intervals[1:]:
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if pre[1] < e[1]:
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cnt += 1
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pre = e
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return cnt
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```
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### **Java**
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```java
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class Solution {
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public int removeCoveredIntervals(int[][] intervals) {
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Arrays.sort(intervals, (a, b) -> a[0] - b[0] == 0 ? b[1] - a[1] : a[0] - b[0]);
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int[] pre = intervals[0];
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int cnt = 1;
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for (int i = 1; i < intervals.length; ++i) {
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if (pre[1] < intervals[i][1]) {
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++cnt;
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pre = intervals[i];
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}
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}
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return cnt;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
128+
public:
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int removeCoveredIntervals(vector<vector<int>> &intervals) {
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sort(intervals.begin(), intervals.end(), [](const vector<int> &a, const vector<int> &b)
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{ return a[0] == b[0] ? b[1] < a[1] : a[0] < b[0]; });
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int cnt = 1;
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vector<int> pre = intervals[0];
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for (int i = 1; i < intervals.size(); ++i)
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{
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if (pre[1] < intervals[i][1])
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{
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++cnt;
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pre = intervals[i];
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}
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}
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return cnt;
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}
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};
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```
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### **Go**
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```go
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func removeCoveredIntervals(intervals [][]int) int {
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sort.Slice(intervals, func(i, j int) bool {
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if intervals[i][0] == intervals[j][0] {
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return intervals[j][1] < intervals[i][1]
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}
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return intervals[i][0] < intervals[j][0]
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})
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cnt := 1
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pre := intervals[0]
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for i := 1; i < len(intervals); i++ {
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if pre[1] < intervals[i][1] {
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cnt++
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pre = intervals[i]
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}
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}
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return cnt
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}
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```
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### **...**

Diff for: ‎solution/1200-1299/1288.Remove Covered Intervals/Solution.cpp

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
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class Solution {
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public:
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int removeCoveredIntervals(vector<vector<int>> &intervals) {
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sort(intervals.begin(), intervals.end(), [](const vector<int> &a, const vector<int> &b)
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{ return a[0] == b[0] ? b[1] < a[1] : a[0] < b[0]; });
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int cnt = 1;
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vector<int> pre = intervals[0];
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for (int i = 1; i < intervals.size(); ++i)
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{
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if (pre[1] < intervals[i][1])
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{
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++cnt;
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pre = intervals[i];
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}
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}
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return cnt;
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}
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};

Diff for: ‎solution/1200-1299/1288.Remove Covered Intervals/Solution.go

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func removeCoveredIntervals(intervals [][]int) int {
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sort.Slice(intervals, func(i, j int) bool {
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if intervals[i][0] == intervals[j][0] {
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return intervals[j][1] < intervals[i][1]
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}
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return intervals[i][0] < intervals[j][0]
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})
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cnt := 1
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pre := intervals[0]
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for i := 1; i < len(intervals); i++ {
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if pre[1] < intervals[i][1] {
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cnt++
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pre = intervals[i]
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}
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}
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return cnt
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}

Diff for: ‎solution/1200-1299/1288.Remove Covered Intervals/Solution.java

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Original file line numberDiff line numberDiff line change
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class Solution {
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public int removeCoveredIntervals(int[][] intervals) {
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Arrays.sort(intervals, (a, b) -> a[0] - b[0] == 0 ? b[1] - a[1] : a[0] - b[0]);
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int[] pre = intervals[0];
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int cnt = 1;
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for (int i = 1; i < intervals.length; ++i) {
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if (pre[1] < intervals[i][1]) {
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++cnt;
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pre = intervals[i];
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}
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}
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return cnt;
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}
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}

Diff for: ‎solution/1200-1299/1288.Remove Covered Intervals/Solution.py

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Original file line numberDiff line numberDiff line change
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class Solution:
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def removeCoveredIntervals(self, intervals: List[List[int]]) -> int:
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intervals.sort(key=lambda x: (x[0], -x[1]))
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cnt, pre = 1, intervals[0]
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for e in intervals[1:]:
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if pre[1] < e[1]:
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cnt += 1
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pre = e
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return cnt

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