Merge pull request youngyangyang04#1170 from xiaofei-2020/back03

添加（0077.组合优化.md）：增加typescript版本

Author: youngyangyang04

problems/0077.组合优化.md

@@ -240,7 +240,29 @@ var combine = function(n, k) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function combine(n: number, k: number): number[][] {
+    let resArr: number[][] = [];
+    function backTracking(n: number, k: number, startIndex: number, tempArr: number[]): void {
+        if (tempArr.length === k) {
+            resArr.push(tempArr.slice());
+            return;
+        }
+        for (let i = startIndex; i <= n - k + 1 + tempArr.length; i++) {
+            tempArr.push(i);
+            backTracking(n, k, i + 1, tempArr);
+            tempArr.pop();
+        }
+    }
+    backTracking(n, k, 1, []);
+    return resArr;
+};
+```
+
 C:
+
 ```c
 int* path;
 int pathTop;