136. Single Number

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136. Single Number

Description

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

You must implement a solution with a linear runtime complexity and use only constant extra space.

Example 1:

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

Example 2:

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

Example 3:

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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.

Hints/Notes

Solution

Language: C++

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class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int res = 0;
        for (int& num : nums) {
            res ^= num;
        }
        return res;
    }
};