添加 0376.摆动序列.md C语言

problems/0376.摆动序列.md

@@ -298,5 +298,32 @@ var wiggleMaxLength = function(nums) {
 };
 ```
 
+### C
+**贪心**
+```c
+int wiggleMaxLength(int* nums, int numsSize){
+    if(numsSize <= 1) 
+        return numsSize;
+
+    int length = 1;
+    int preDiff , curDiff;
+    preDiff = curDiff = 0;
+    for(int i = 0; i < numsSize - 1; ++i) {
+        // 计算当前i元素与i+1元素差值
+        curDiff = nums[i+1] - nums[i];
+
+        // 若preDiff与curDiff符号不符，则子序列长度+1。更新preDiff的符号
+        // 若preDiff与curDiff符号一致，当前i元素为连续升序/连续降序子序列的中间元素。不被记录入长度
+        // 注：当preDiff为0时，curDiff为正或为负都属于符号不同
+        if((curDiff > 0 && preDiff <= 0) || (preDiff >= 0 && curDiff < 0)) {
+            preDiff = curDiff;
+            length++;
+        }
+    }
+
+    return length;
+}
+```
+
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>