Single Number
Implement singleNumber
Somewhere in this array, exactly one value breaks the pattern — everything else shows up in a matching pair, but one number stands alone with no partner. Find it.
Order doesn't matter here, and there's no need to track which values you've already seen: XOR-ing every element together in a single pass cancels every paired value down to nothing (since
x ^ x = 0), leaving only the unpaired value behind.
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
+ 10 hidden test cases run on Submit.
Constraints:
- ●
1 ≤ nums.length ≤ 3 × 10⁴ - ●
-3 × 10⁴ ≤ nums[i] ≤ 3 × 10⁴ - ●
Every value in nums appears exactly twice, except for one value which appears exactly once
nums =
[2, 2, 1]