Description
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.
Code
和 Missing Number 中用到的觀念一樣。 XOR 觀念：XOR 同一個數字兩字等於 no-op。
class Solution {
public:
int singleNumber(vector<int>& nums) {
int res = 0;
for(auto num: nums) {
res ^= num;
}
return res;
}
};