The kth Factor of n

Given two positive integers n and k.

A factor of an integer n is defined as an integer i where n % i == 0.

Consider a list of all factors of n sorted in ascending order, return the kth factor in this list or return -1 if n has less than k factors.

Example 1: 

Input: n = 12, k = 3
Output: 3
Explanation: Factors list is [1, 2, 3, 4, 6, 12], the 3rd factor is 3.

Example 2: 

Input: n = 7, k = 2
Output: 7
Explanation: Factors list is [1, 7], the 2nd factor is 7.

Example 3: 

Input: n = 4, k = 4
Output: -1
Explanation: Factors list is [1, 2, 4], there is only 3 factors. We should return -1.

Example 4: 

Input: n = 1, k = 1
Output: 1
Explanation: Factors list is [1], the 1st factor is 1.

Example 5: 

Input: n = 1000, k = 3
Output: 4
Explanation: Factors list is [1, 2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 125, 200, 250, 500, 1000].

Constraints:

  • 1 <= k <= n <= 1000
Solution:

class Solution {
    public int kthFactor(int n, int k) {
        int i, m=0;
        for(i=1;i<=n;i++){
            if(n%i==0){
                m++;
                if(m==k){
                    return i;
                }
            }
        }
        return -1;
    }
}


Here, it contains lot of ways to solve the problem. But, we are going to finish in more optimized way.

1) We are going to iterate i variable from 1 to till n.
2) For each factor, increase m [acts as count to equal k]. If m equals to k, return i which will be the required output.
3) If iteration goes beyond n, then final return -1 will be executed

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