136. Single Number #

Problem Statement #

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:

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 * 104
• -3 * 104 <= nums[i] <= 3 * 104
• Each element in the array appears twice except for one element which appears only once.

Solution: #

impl Solution {
    pub fn single_number(nums: Vec<i32>) -> i32 {
        let mut res = 0;
        for num in nums {
            // a ^ a = 0
            // a ^ a ^ a = a
            // a ^ a ^ b = b
            // also position of a and b doesn't matter
            res ^= num;
        }

        res
    }
}

... #