Algorithm
A. k-th divisor
time limit per test
2 secondsmemory limit per test
256 megabytesProblem link- https://codeforces.com/problemset/problem/762/A
input
standard inputoutput
standard outputYou are given two integers n and k. Find k-th smallest divisor of n, or report that it doesn't exist.
Divisor of n is any such natural number, that n can be divided by it without remainder.
Input
The first line contains two integers n and k (1 ≤ n ≤ 1015, 1 ≤ k ≤ 109).
Output
If n has less than k divisors, output -1.
Otherwise, output the k-th smallest divisor of n.
Examples
input
Copy
4 2
output
Copy
2
input
Copy
5 3
output
Copy
-1
input
Copy
12 5
output
Copy
6
Note
In the first example, number 4 has three divisors: 1, 2 and 4. The second one is 2.
In the second example, number 5 has only two divisors: 1 and 5. The third divisor doesn't exist, so the answer is -1.
Code Examples
#1 Code Example with C++ Programming
Code -
C++ Programming
#include <bits/stdc++.h>
using namespace std;
vector<long long> d;
long long n, k;
int main() {
scanf("%lld %lld", &n, &k);
for(int i = 1; 1ll * i * i <= n; ++i) {
if(n % i == 0) {
d.push_back(i);
if(n / i != i)
d.push_back(n / i);
}
}
sort(d.begin(), d.end());
if(d.size() < k) {
puts("-1");
return 0;
}
printf("%lld\n", d[k - 1]);
return 0;
}Input
4 2
Output
2
Demonstration
Codeforces Solution-k-th divisor-Solution in C, C++, Java, Python