solve problem Single Element In A Sorted Array

Author: P-ppc

README.md

@@ -244,6 +244,7 @@ All solutions will be accepted!
 |442|[Find All Duplicates In An Array](https://leetcode-cn.com/problems/find-all-duplicates-in-an-array/description/)|[java/py/js](./algorithms/FindAllDuplicatesInAnArray)|Medium|
 |64|[Minimum Path Sum](https://leetcode-cn.com/problems/minimum-path-sum/description/)|[java/py/js](./algorithms/MinimumPathSum)|Medium|
 |535|[Encode And Decode Tinyurl](https://leetcode-cn.com/problems/encode-and-decode-tinyurl/description/)|[java/py/js](./algorithms/EncodeAndDecodeTinyurl)|Medium|
+|540|[Single Element In A Sorted Array](https://leetcode-cn.com/problems/single-element-in-a-sorted-array/description/)|[java/py/js](./algorithms/SingleElementInASortedArray)|Medium|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/SingleElementInASortedArray/README.md

@@ -0,0 +1,2 @@
+# Single Element In A Sorted Array
+We can solve this problem by Binary Search

algorithms/SingleElementInASortedArray/Solution.java

@@ -0,0 +1,22 @@
+class Solution {
+    public int singleNonDuplicate(int[] nums) {
+        int left = 0,
+            right = nums.length - 1;
+        
+        while (left < right) {
+            int mid = (left + right) / 2;
+            
+            if (nums[mid] == nums[mid + 1]) {
+                if (mid % 2 == 0) left = mid + 1;
+                else right = mid - 1;
+            } else if (nums[mid] == nums[mid - 1]) {
+                if (mid % 2 == 0) right = mid - 1;
+                else left = mid + 1;
+            } else {
+                return nums[mid];
+            }
+        }
+        
+        return nums[left];
+    }
+}

algorithms/SingleElementInASortedArray/solution.js

@@ -0,0 +1,24 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var singleNonDuplicate = function(nums) {
+    let left = 0,
+        right = nums.length - 1
+    
+    while (left < right) {
+        let mid = parseInt((left + right) / 2)
+        
+        if (nums[mid] === nums[mid + 1]) {
+            if (mid % 2 === 0) left = mid + 1
+            else right = mid - 1
+        } else if (nums[mid] === nums[mid - 1]) {
+            if (mid % 2 === 0) right = mid - 1
+            else left = mid + 1
+        } else {
+            return nums[mid]
+        }
+    }
+    
+    return nums[left]
+};

algorithms/SingleElementInASortedArray/solution.py

@@ -0,0 +1,22 @@
+class Solution(object):
+    def singleNonDuplicate(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        left = 0
+        right = len(nums) - 1
+        
+        while left < right:
+            mid = (left + right) / 2
+            
+            if nums[mid] == nums[mid - 1]:
+                if mid % 2 == 0: right = mid - 1
+                else: left = mid + 1
+            elif nums[mid] == nums[mid + 1]:
+                if mid % 2 == 0: left = mid + 1
+                else: right = mid - 1
+            else:
+                return nums[mid]
+        
+        return nums[left]