添加（0239.滑动窗口最大值.md）：增加typescript版本

problems/0239.滑动窗口最大值.md

@@ -418,7 +418,56 @@ var maxSlidingWindow = function (nums, k) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function maxSlidingWindow(nums: number[], k: number): number[] {
+    /** 单调递减队列 */
+    class MonoQueue {
+        private queue: number[];
+        constructor() {
+            this.queue = [];
+        };
+        /** 入队：value如果大于队尾元素，则将队尾元素删除，直至队尾元素大于value，或者队列为空 */
+        public enqueue(value: number): void {
+            let back: number | undefined = this.queue[this.queue.length - 1];
+            while (back !== undefined && back < value) {
+                this.queue.pop();
+                back = this.queue[this.queue.length - 1];
+            }
+            this.queue.push(value);
+        };
+        /** 出队：只有当队头元素等于value，才出队 */
+        public dequeue(value: number): void {
+            let top: number | undefined = this.top();
+            if (top !== undefined && top === value) {
+                this.queue.shift();
+            }
+        }
+        public top(): number | undefined {
+            return this.queue[0];
+        }
+    }
+    const helperQueue: MonoQueue = new MonoQueue();
+    let i: number = 0,
+        j: number = 0;
+    let resArr: number[] = [];
+    while (j < k) {
+        helperQueue.enqueue(nums[j++]);
+    }
+    resArr.push(helperQueue.top()!);
+    while (j < nums.length) {
+        helperQueue.enqueue(nums[j]);
+        helperQueue.dequeue(nums[i]);
+        resArr.push(helperQueue.top()!);
+        j++, i++;
+    }
+    return resArr;
+};
+```
+
 Swift:
+
 ```Swift
 /// 双向链表
 class DoublyListNode {