@@ -55,11 +55,11 @@
 | [Graph](https://.com/fluency03/leetcode-java/blob/master/src/graph) |
 
 
-# Total: 532
+# Total: 533
 
 | Easy | Medium | Hard | - |
 |:-------:|:-------:|:----:|:---:|
-| 142 | 288 | 90 | 12 |
+| 142 | 289 | 90 | 12 |
 
 
 | Question | Solution | Difficulty |
@@ -104,6 +104,7 @@
 | [47. Permutations II](https://leetcode.com/problems/permutations-ii/) | [Solution](https://.com/fluency03/leetcode-java/blob/master/src/PermutationsII47.java) | Medium |
 | [48. Rotate Image](https://leetcode.com/problems/rotate-image/) | [Solution](https://.com/fluency03/leetcode-java/blob/master/src/RotateImage48.java) | Medium |
 | [49. Group Anagrams](https://leetcode.com/problems/group-anagrams/) | [Solution](https://.com/fluency03/leetcode-java/blob/master/src/GroupAnagrams49.java) | Medium |
+| [50. Pow(x, n)](https://leetcode.com/problems/powx-n/) | [Solution](https://.com/fluency03/leetcode-java/blob/master/src/PowXN50.java) | Medium |
 | [51. N-Queens](https://leetcode.com/problems/n-queens/) | [Solution](https://.com/fluency03/leetcode-java/blob/master/src/NQueens51.java) | Hard |
 | [52. N-Queens II](https://leetcode.com/problems/n-queens-ii/) | [Solution](https://.com/fluency03/leetcode-java/blob/master/src/NQueensII52.java) | Hard |
 | [53. Maximum Subarray](https://leetcode.com/problems/maximum-subarray/) | [Solution](https://.com/fluency03/leetcode-java/blob/master/src/MaximumSubarray53.java) | Easy |

@@ -0,0 +1,68 @@
+/**
+* Implement pow(x, n), which calculates x raised to the power n (xn).
+*
+* Example 1:
+* Input: 2.00000, 10
+* Output: 1024.00000
+*
+* Example 2:
+* Input: 2.10000, 3
+* Output: 9.26100
+*
+* Example 3:
+* Input: 2.00000, -2
+* Output: 0.25000
+* Explanation: 2-2 = 1/22 = 1/4 = 0.25
+*
+* Note:
+* -100.0 < x < 100.0
+* n is a 32-bit signed integer, within the range [−231, 231 − 1]
+*/
+
+public class PowXN50 {
+/**
+* https://leetcode.com/problems/powx-n/solution/
+*/
+public double myPow(double x, int n) {
+long N = n;
+if (N < 0) {
+x = 1 / x;
+N = -N;
+}
+return fastPow(x, N);
+}
+
+private double fastPow(double x, long n) {
+if (n == 0) {
+return 1.0;
+}
+double half = fastPow(x, n / 2);
+if (n % 2 == 0) {
+return half * half;
+} else {
+return half * half * x;
+}
+}
+
+
+/**
+* https://leetcode.com/problems/powx-n/solution/
+*/
+public double myPow2(double x, int n) {
+long N = n;
+if (N < 0) {
+x = 1 / x;
+N = -N;
+}
+double ans = 1;
+double current_product = x;
+for (long i = N; i > 0; i /= 2) {
+if ((i % 2) == 1) {
+ans = ans * current_product;
+}
+current_product = current_product * current_product;
+}
+return ans;
+}
+
+}