Find the Duplicate Number | LeetCode | Run TIme O(n)

 Statement - Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive.

There is only one repeated number in nums, return this repeated number.

Example 1:

Input: nums = [1,3,4,2,2]
Output: 2

Problem Link - Click

Code - Run Time O(n) and Space Complexity O(1).

class Solution {
public:
    int findDuplicate(vector<int>& nums) {
        
        for(int i = 0; i < nums.size(); i++)
        {
            if(nums[abs(nums[i])] < 0)
                return abs(nums[i]);
                
                
            nums[abs(nums[i])] *= -1;
        }
        
        return 0;
    }
};