// just brute on instance 0
#include "message.h"
#include "futbol.h"
#include "bits/stdc++.h"
using namespace std;
int pow(int x, unsigned int y, int p) {
int res = 1;
x = x % p;
while (y > 0) {
if (y & 1)
res = res * int64_t(x) % p;
y /= 2;
x = x * int64_t(x) % p;
}
return res;
}
uint32_t ps_ncr(uint32_t n, uint32_t k, uint32_t p) {
if (k == n) {
return pow(2, n, p);
}
if (2 * k + 1 == n) {
return pow(2, n - 1, p);
}
if (2 * k > n) {
return (pow(2, n, p) - ps_ncr(n, n - k - 1, p) + p) % p;
}
uint64_t num = 1;
uint64_t den = 1;
uint64_t res = 1;
for (int i = 0; i < k; i++) {
num = (num * (n - i)) % p;
den = (den * (i + 1)) % p;
res = (res + num * pow(den, p - 2, p)) % p;
}
return res;
}
int main() {
if(MyNodeId() != 0) return 0;
int n = GetN(), k = GetK(), p = GetP();
//int n = 440581, k = 133004, p = 144495917;
//int n = 10, k=3, p=13;
cout << ps_ncr(n, k, p) << endl;
}
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | // just brute on instance 0 #include "message.h" #include "futbol.h" #include "bits/stdc++.h" using namespace std; int pow(int x, unsigned int y, int p) { int res = 1; x = x % p; while (y > 0) { if (y & 1) res = res * int64_t(x) % p; y /= 2; x = x * int64_t(x) % p; } return res; } uint32_t ps_ncr(uint32_t n, uint32_t k, uint32_t p) { if (k == n) { return pow(2, n, p); } if (2 * k + 1 == n) { return pow(2, n - 1, p); } if (2 * k > n) { return (pow(2, n, p) - ps_ncr(n, n - k - 1, p) + p) % p; } uint64_t num = 1; uint64_t den = 1; uint64_t res = 1; for (int i = 0; i < k; i++) { num = (num * (n - i)) % p; den = (den * (i + 1)) % p; res = (res + num * pow(den, p - 2, p)) % p; } return res; } int main() { if(MyNodeId() != 0) return 0; int n = GetN(), k = GetK(), p = GetP(); //int n = 440581, k = 133004, p = 144495917; //int n = 10, k=3, p=13; cout << ps_ncr(n, k, p) << endl; } |
English