Single Number LeetCode Solution - The Coding Shala

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 In this post, we will learn how to solve LeetCode's Single Number Problem and will implement its solution in Java.

Single Number Problem

Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.

Example 1:
Input: nums = [2,2,1]
Output: 1

Example 2:
Input: nums = [4,1,2,1,2]
Output: 4

Practice this problem on LeetCode(Click Here).

Single Number Java Solution

Approach 1

We can use the bitwise xor (^) operation. We know that the xor of two same numbers is zero and the xor of a number with zero is the same as the number.

Time Complexity: O(n).

Space Complexity: O(1).

Java Program: 

class Solution {
    public int singleNumber(int[] nums) {
        int ans = nums[0];
        //xor of two same numbers is zero
        for(int i=1; i<nums.length; i++) {
            ans = ans ^ nums[i];
        return ans;

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