feat: azl397985856#209: add C++ implementation (azl397985856#89)

problems/209.minimum-size-subarray-sum.md

@@ -31,6 +31,10 @@ If you have figured out the O(n) solution, try coding another solution of which
 
 ## 代码
 
+* 语言支持：JS，C++
+
+JavaScript Code：
+
 ```js
 /*
  * @lc app=leetcode id=209 lang=javascript
@@ -93,6 +97,26 @@ var minSubArrayLen = function(s, nums) {
 };
 ```
 
+C++ Code：
+```C++
+class Solution {
+public:
+    int minSubArrayLen(int s, vector<int>& nums) {
+        int num_len= nums.size();
+        int left=0, right=0, total=0, min_len= num_len+1;
+        while (right < num_len) {
+            do {
+                total += nums[right++];
+            } while (right < num_len && total < s);
+            while (left < right && total - nums[left] >= s) total -= nums[left++];
+            if (total >=s && min_len > right - left) 
+                min_len = right- left;
+        }
+        return min_len <= num_len ? min_len: 0;
+    }
+};
+```
+
 ## 扩展
 
 如果题目要求是 sum = s, 而不是 sum >= s 呢？