single_number.rs

/// 
/// Problem: Single Number
/// 
/// 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 * 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.
/// 

// # Solution 1: XOR approach
// Time complexity: O(n) where n is the length of the array
// Space complexity: O(1) - We only use a single variable

impl Solution {
    pub fn single_number(nums: Vec<i32>) -> i32 {
        let mut result = 0;
       
       for num in nums {
           result ^= num;
       }
       
       result
    }
}