添加（0001.两数之和.md）：增加typescript版本

problems/0001.两数之和.md

@@ -186,6 +186,24 @@ var twoSum = function (nums, target) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function twoSum(nums: number[], target: number): number[] {
+    let helperMap: Map<number, number> = new Map();
+    let index: number | undefined;
+    let resArr: number[] = [];
+    for (let i = 0, length = nums.length; i < length; i++) {
+        index = helperMap.get(target - nums[i]);
+        if (index !== undefined) {
+            resArr = [i, index];
+        }
+        helperMap.set(nums[i], i);
+    }
+    return resArr;
+};
+```
+
 php
 
 ```php