Leetcode 540 Single Element in a Sorted Array

Given a sorted array consisting of only integers where every element appears twice except for one element which appears once. Find this single element that appears only once.

Example 1:

Input: [1,1,2,3,3,4,4,8,8]Output: 2

Example 2:

Input: [3,3,7,7,10,11,11]Output: 10

Note: Your solution should run in O(log n) time and O(1) space.

因为题目要求是O（logn）了，那么肯定是想到用binary search

这个问题有一个需要注意的地方就是如果一个序列都是俩俩重复 

比如 1 1 2 2 3 3。。那么第0位和第1位元素一定是相同的 也就是2m 和2m+1位

但是如果一旦出现一个不重复的 后面的序号关系就全部变了 

public class Solution {    public int singleNonDuplicate(int[] nums) {        int low = 0;        int high = nums.length / 2;        while(low < high){            int mid = low + (high - low) / 2;            if(nums[2 * mid] != nums[2 * mid + 1]){                high = mid;            }else{                low = mid + 1;            }        }        return nums[2 * low];    }}