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
classSolution {intkthFactor(int n,int k) {int number =1;// O(rootN)for (; number * number <= n; ++number)if (n % number ==0) { k--;if (k ==0)return number; }// O(rootN)for (number = number -1; number >=1; number--) {// Skipping number * number == n, because this would have been counted in first// loopif (number * number == n)continue;if (n % number ==0&&--k ==0)return n / number; }return-1; }}