136. Single Number (Easy)

Given an array of integers, every element appears twice except for
one. Find that single one.

Note: Your algorithm should have a linear runtime complexity. Could
you implement it without using extra memory?

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Solutions:

C:

#include<stdio.h>int singleNumber(int* nums, int numsSize) {    int i;    int result = nums[0];    for(i = 1; i < numsSize; i++) {        result ^= nums[i];    }    return result;}int main() {    int arr[] = {2, 2, 5, 5, 6, 7, 7};    printf("%d", singleNumber(arr, 7));     return 0;} 

思路：使用^运算符，a^b^a=b