Merge pull request #958 from Tiffany-yuan/master

update: 0376.摆动序列 js动态规划解法

problems/0376.摆动序列.md

@@ -261,6 +261,7 @@ func wiggleMaxLength(nums []int) int {
 ```
 
 ### Javascript 
+**贪心**
 ```Javascript
 var wiggleMaxLength = function(nums) {
     if(nums.length <= 1) return nums.length
@@ -277,6 +278,25 @@ var wiggleMaxLength = function(nums) {
     return result
 };
 ```
+**动态规划**
+```Javascript
+var wiggleMaxLength = function(nums) {
+    if (nums.length === 1) return 1; 
+    // 考虑前i个数，当第i个值作为峰谷时的情况（则第i-1是峰顶）
+    let down = 1;
+    // 考虑前i个数，当第i个值作为峰顶时的情况（则第i-1是峰谷）
+    let up = 1;
+    for (let i = 1; i < nums.length; i++) {
+        if (nums[i] < nums[i - 1]) {
+            down = Math.max(up + 1, down);
+        }
+        if (nums[i] > nums[i - 1]) {
+            up = Math.max(down + 1, up)
+        }
+    }
+    return Math.max(down, up);
+};
+```
 
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