540. Single Element in a Sorted Array #

Problem Statement #

You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once.

Return the single element that appears only once.

Your solution must run in O(log n) time and O(1) space.

Example 1:

Input: nums = [1,1,2,3,3,4,4,8,8]
Output: 2

Example 2:

Input: nums = [3,3,7,7,10,11,11]
Output: 10

Constraints:

• 1 <= nums.length <= 105
• 0 <= nums[i] <= 105

Solution: #

package main

func singleNonDuplicate(nums []int) int {
	res := 0

	for _, num := range nums {
		// a ^ a = 0
		// a ^ a ^ a = a
		// a ^ a ^ b = b
		// also position of a and b doesn't matter
		res ^= num
	}

	return res
}

impl Solution {
    pub fn single_non_duplicate(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
    }
}

... #