update: 50

Author: hijiangtao

README.md

@@ -41,6 +41,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr
 | 46 | [Permutations](https://leetcode.com/problems/permutations/) | [JavaScript](./src/permutations/res.js) | Medium |
 | 48 | [Rotate Image](https://leetcode.com/problems/rotate-image/) | [JavaScript](./src/rotate-image/res.js) | Medium |
 | 49 | [Group Anagrams](https://leetcode.com/problems/anagrams/) | [JavaScript](./src/anagrams/res.js) | Medium |
+| 50 | [powx-n](https://leetcode.com/problems/powx-n/) | [TypeScript](./src/powx-n/res.ts) | Medium |
 | 53 | [Maximum Subarray](https://leetcode.com/problems/maximum-subarray/) | [JavaScript](./src/maximum-subarray/res.js) · [TypeScript](./src/maximum-subarray/res.ts) | Easy |
 | 54 | [Spiral Matrix](https://leetcode.com/problems/spiral-matrix/) | [JavaScript](./src/spiral-matrix/res.js) | Medium |
 | 55 | [Jump Game](https://leetcode.com/problems/jump-game/) <sup>*</sup> | [JavaScript](./src/jump-game/res.js) | Medium |

src/powx-n/res.ts

@@ -0,0 +1,15 @@
+function myPow(x: number, n: number): number {
+if (n === 0) {
+return 1;
+} else if (n === 1) {
+return x;
+} else if (n > 0) {
+if (n % 2 === 0) {
+return myPow(x*x, n/2);
+} else {
+return x * myPow(x, n-1);
+}
+} else {
+return 1 / myPow(x, -n);
+}
+};