【LeetCode】136. Single Number

問題描述

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?

解決方法

//複雜度爲O(n)
/*
we use bitwise XOR to solve this problem :

first , we have to know the bitwise XOR in java

0 ^ N = N
N ^ N = 0
So..... if N is the single number

N1 ^ N1 ^ N2 ^ N2 ^..............^ Nx ^ Nx ^ N

= (N1^N1) ^ (N2^N2) ^..............^ (Nx^Nx) ^ N

= 0 ^ 0 ^ ..........^ 0 ^ N

= N
*/
class Solution
{
    public static int singleNumber(int[] nums)
    {
        int result = 0;
        for(int i:nums)
        {
            result ^= i;
        }
        return result;
    }
}