136.single-number.cpp

/*
 * @lc app=leetcode id=136 lang=cpp
 *
 * [136] Single Number
 *
 * https://leetcode.com/problems/single-number/description/
 *
 * algorithms
 * Easy (66.31%)
 * Likes:    5841
 * Dislikes: 191
 * Total Accepted:    1.1M
 * Total Submissions: 1.7M
 * Testcase Example:  '[2,2,1]'
 *
 * Given a non-empty array of integers nums, every element appears twice except
 * for one. Find that single one.
 * 
 * Follow up: Could you implement a solution with a linear runtime complexity
 * and without using extra memory?
 * 
 * 
 * Example 1:
 * Input: nums = [2,2,1]
 * Output: 1
 * Example 2:
 * Input: nums = [4,1,2,1,2]
 * Output: 4
 * Example 3:
 * Input: nums = [1]
 * Output: 1
 * 
 * 
 * Constraints:
 * 
 * 
 * 1 <= nums.length <= 3 * 10^4
 * -3 * 10^4 <= nums[i] <= 3 * 10^4
 * Each element in the array appears twice except for one element which appears
 * only once.
 * 
 * 
 */

// @lc code=start
class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int xorbit = 0;
        for (const auto& ele : nums)
            xorbit ^= ele;
        return xorbit;
    }
};
// @lc code=end