'Single Number' soln

Author: joewnga

leetcode/single_number.rs

@@ -0,0 +1,42 @@
+/// 
+/// 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
+    }
+}