Merge pull request youngyangyang04#1194 from xiaofei-2020/back15

添加（0046.全排列.md）：增加typesript版本

Author: youngyangyang04

problems/0046.全排列.md

@@ -331,6 +331,34 @@ var permute = function(nums) {
 
 ```
 
+## TypeScript
+
+```typescript
+function permute(nums: number[]): number[][] {
+    const resArr: number[][] = [];
+    const helperSet: Set<number> = new Set();
+    backTracking(nums, []);
+    return resArr;
+    function backTracking(nums: number[], route: number[]): void {
+        if (route.length === nums.length) {
+            resArr.push(route.slice());
+            return;
+        }
+        let tempVal: number;
+        for (let i = 0, length = nums.length; i < length; i++) {
+            tempVal = nums[i];
+            if (!helperSet.has(tempVal)) {
+                route.push(tempVal);
+                helperSet.add(tempVal);
+                backTracking(nums, route);
+                route.pop();
+                helperSet.delete(tempVal);
+            }
+        }
+    }
+};
+```
+
 ### C
 
 ```c