diff --git a/problems/0209.长度最小的子数组.md b/problems/0209.长度最小的子数组.md
index 17422ca0..dc1d9f18 100644
--- a/problems/0209.长度最小的子数组.md
+++ b/problems/0209.长度最小的子数组.md
@@ -330,5 +330,55 @@ def min_sub_array_len(target, nums)
 end
 ```
 
+C:
+暴力解法:
+```c
+int minSubArrayLen(int target, int* nums, int numsSize){
+    //初始化最小长度为INT_MAX
+    int minLength = INT_MAX;
+    int sum;
+
+    int left, right;
+    for(left = 0; left < numsSize; ++left) {
+        //每次遍历都清零sum，计算当前位置后和>=target的子数组的长度
+        sum = 0;
+        //从left开始，sum中添加元素
+        for(right = left; right < numsSize; ++right) {
+            sum += nums[right];
+            //若加入当前元素后，和大于target，则更新minLength
+            if(sum >= target) {
+                int subLength = right - left + 1;
+                minLength = minLength < subLength ? minLength : subLength;
+            }
+        }
+    }
+    //若minLength不为INT_MAX，则返回minLnegth
+    return minLength == INT_MAX ? 0 : minLength;
+}
+```
+
+滑动窗口:
+```c
+int minSubArrayLen(int target, int* nums, int numsSize){
+    //初始化最小长度为INT_MAX
+    int minLength = INT_MAX;
+    int sum = 0;
+
+    int left = 0, right = 0; 
+    //右边界向右扩展
+    for(; right < numsSize; ++right) {
+        sum += nums[right];
+        //当sum的值大于等于target时，保存长度，并且收缩左边界
+        while(sum >= target) {
+            int subLength = right - left + 1;
+            minLength = minLength < subLength ? minLength : subLength;
+            sum -= nums[left++];
+        }
+    }
+    //若minLength不为INT_MAX，则返回minLnegth
+    return minLength == INT_MAX ? 0 : minLength;
+}
+```
+
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