Single Number II

Problem Statement - link #

Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it.

You must implement a solution with a linear runtime complexity and use only constant extra space.

Examples #

Example 1:

Input: nums = [2,2,3,2]
Output: 3

Example 2:

Input: nums = [0,1,0,1,0,1,99]
Output: 99

Constraints #

• 1 <= nums.length <= 3 * 10^4
• -2^31 <= nums[i] <= 2^31 - 1
• Each element in nums appears exactly three times except for one element which appears once.

Solutions #

class Solution {
public:
    int singleNumber(vector<int>& nums) {
      sort(nums.begin(), nums.end());
      int c = 1, n=nums[0];
      for(auto i: nums) cout<<i<<" ";
      for(int i=1; i<nums.size(); i++){
        if(n==nums[i]) c++;
        else if(c==1) return n;
        else { c = 1; n = nums[i]; }
      }
      return n;
    }
};