添加 0239.滑动窗口最大值.md C 版本

Author: c-qwer

problems/0239.滑动窗口最大值.md

@@ -890,6 +890,38 @@ public:
 };
 ```
 
+### C
+
+```c
+int* maxSlidingWindow(int* nums, int numsSize, int k, int* returnSize) {
+    *returnSize = numsSize - k + 1;
+    int *res = (int*)malloc((*returnSize) * sizeof(int));
+    assert(res);
+    int *deque = (int*)malloc(numsSize * sizeof(int));
+    assert(deque);
+    int front = 0, rear = 0, idx = 0;
+
+    for (int i  = 0 ; i < numsSize ; i++) {
+        while (front < rear && deque[front] <= i - k) {
+            front++;
+        }
+
+        while (front < rear && nums[deque[rear - 1]] <= nums[i]) {
+            rear--;
+        }
+
+        deque[rear++] = i;
+
+        if (i >= k - 1) {
+            res[idx++] = nums[deque[front]];
+        }
+    }       
+
+    return res;
+}
+
+```
+
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