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:

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.

submission

// since x ^ x == 0 and x ^ 0 == x
// we just XOR every number in nums
impl Solution {
    pub fn single_number(nums: Vec<i32>) -> i32 {
        nums.into_iter()
            .fold(0, |init, val| init ^ val)
    }
}