[LeetCode] 136. Single Number / Swift

[문제 보기]

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.

 

https://leetcode.com/problems/single-number/

Single Number - LeetCode

 

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추가공간을 상수로 쓰라고하는 부분에서 막혔다.

다른 사람 풀이를 보니 xor 연산을 이용하는 문제였다.

class Solution {
    func singleNumber(_ nums: [Int]) -> Int {
        var ans = 0
        for element in nums {
            ans ^= element
        }
        return ans
    }
}

https://www.youtube.com/watch?v=5ATrVxnxINE