Merge pull request #737 from martisss/master

增加435.无重叠区间 js解法

problems/0435.无重叠区间.md

@@ -274,6 +274,7 @@ func min(a,b int)int{
 }
 ```
 Javascript:
+- 按右边界排序
 ```Javascript
 var eraseOverlapIntervals = function(intervals) {
     intervals.sort((a, b) => {
@@ -285,7 +286,7 @@ var eraseOverlapIntervals = function(intervals) {
 
     for(let i = 1; i < intervals.length; i++) {
         let interval = intervals[i]
-        if(interval[0] >= right) {
+        if(interval[0] >= end) {
             end = interval[1]
             count += 1
         }
@@ -294,6 +295,24 @@ var eraseOverlapIntervals = function(intervals) {
     return intervals.length - count
 };
 ```
+- 按左边界排序
+```js
+var eraseOverlapIntervals = function(intervals) {
+    // 按照左边界升序排列
+    intervals.sort((a, b) => a[0] - b[0])
+    let count = 1
+    let end = intervals[intervals.length - 1][0]
+    // 倒序遍历，对单个区间来说，左边界越大越好，因为给前面区间的空间越大
+    for(let i = intervals.length - 2; i >= 0; i--) {
+        if(intervals[i][1] <= end) {
+            count++
+            end = intervals[i][0]
+        }
+    }
+    // count 记录的是最大非重复区间的个数
+    return intervals.length - count
+}
+```
 
 
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