Leetcode--136. Single Number(easy)

Given a non-empty 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?

Example 1:

Input: [2,2,1]
Output: 1

Example 2:

Input: [4,1,2,1,2]
Output: 4

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

 

silly solution

class Solution {
    public int singleNumber(int[] nums) {
        Map<Integer,Integer> mp=new HashMap<Integer,Integer>();
        for(int i:nums){
            mp.put(i,mp.getOrDefault(i,0)+1);
        }
        for(int i:mp.keySet()){
            if(mp.get(i)<2){
                return i;
            }
        }
        return 0;
    }
}