LeetCode-Single Element in a Sorted Array

Description：
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.

题意：给定一个已排序的数组，要求找出在数组中仅出现一次的那个元素（其他所有元素均出现两次）；

解法：考虑异或操作，对于元素a来说

• a ^ a = 0
• a ^ 0 = a

因此，我们对数组中的所有元素进行异或操作，相同的元素异或得到结果0，而0与数组中仅出现一次的元素再异或得到的就是元素本身；其时间复杂度为O(n)；

Java

class Solution {
    public int singleNonDuplicate(int[] nums) {
        int result = 0;
        for (int num : nums) {
            result ^= num;
        }
        return result;
    }
}