137-Single Number II

Description

Given a non-empty array of integers, every element appears three times except for one, which appears exactly once. 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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Example 1:

Input: [2,2,3,2]
Output: 3

Example 2:

Input: [0,1,0,1,0,1,99]
Output: 99

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問題描述

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問題分析

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解法

class Solution {
    public int singleNumber(int[] nums) {
        int x1 = 0,x2 = 0,mask = 0;

        for(int i : nums){
            x2 ^= x1 & i;
            x1 ^= i;
            mask = ~(x1 & x2);
            x2 &= mask;
            x1 &= mask;
        }

        return x1;
    }
}