[算法相关] 136. Single Number--取出非重复数字

 

136. Single Number

 

 

 

 

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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题意：给定一个数组，数组中除了一个元素，其他元素都有两个。找到那个唯一的元素。

 

public class Solution {
    public int singleNumber(int[] nums) {
    HashSet<Integer> set = new HashSet<Integer>();
        for(int i = 0; i <nums.length; i++){
            if(!set.contains(nums[i])){
                set.add(nums[i]);
            }else{
                set.remove(nums[i]);
            }
        }
        int m =set.hashCode();
        return m;
    }
}

使用哈希表做出来的时候，哥哥是很高兴的，但是看到有些人用到了位运算求解，发现世界真大……

int singleNumber(int A[], int n) {
    int result = 0;
    for (int i = 0; i<n; i++)
    {
        result ^=A[i];
    }
    return result;
}

简直完美……

 

原文链接：https://leetcode.com/problems/single-number/