LeetCode知识点总结 - 540

LeetCode 540. Single Element in a Sorted Array

题目

You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once.

Return the single element that appears only once.

Your solution must run in O(log n) time and O(1) space.

思路

Before the single element x pairs start at even indices. At/after the single element x this pattern breaks

答案

classSolution{publicintsingleNonDuplicate(int[]nums){intleft=0,right=nums.length-1;while(left<right){intmid=(left+right)/2;if((mid%2==0&&nums[mid]==nums[mid+1])||(mid%2==1&&nums[mid]==nums[mid-1]))left=mid+1;elseright=mid;}returnnums[left];}}