#include <cstdio> #include "message.h" #include "futbol.h" int pot(int x, int p, int n) { int ret = 1; for (; n; n /= 2) { if (n % 2) { ret = ((long long)ret) * x % p; } x = ((long long)x) * x % p; } return ret; } int odw(int x, int p) { return pot(x, p, p-2); } int main() { int n = GetN(), k = GetK(), p = GetP(); if (MyNodeId() != 0) return 0; int tyl = 0; if (k > n/2) { k = n-k-1; tyl = 1; } int a = 1, b = 1, c = 1; for (int i = 0; i < k; i++) { c = ((long long)c) * (n-i) % p; b = ((long long)b) * (i+1) % p; a = (((long long)a) * (i+1) + c) % p; } // printf("%d %d\n", a, b); a = ((long long)a) * odw(b, p) % p; if (tyl) { a = (pot(2, p, n) + p - a) % p; } printf("%d\n", a); return 0; }
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 | #include <cstdio> #include "message.h" #include "futbol.h" int pot(int x, int p, int n) { int ret = 1; for (; n; n /= 2) { if (n % 2) { ret = ((long long)ret) * x % p; } x = ((long long)x) * x % p; } return ret; } int odw(int x, int p) { return pot(x, p, p-2); } int main() { int n = GetN(), k = GetK(), p = GetP(); if (MyNodeId() != 0) return 0; int tyl = 0; if (k > n/2) { k = n-k-1; tyl = 1; } int a = 1, b = 1, c = 1; for (int i = 0; i < k; i++) { c = ((long long)c) * (n-i) % p; b = ((long long)b) * (i+1) % p; a = (((long long)a) * (i+1) + c) % p; } // printf("%d %d\n", a, b); a = ((long long)a) * odw(b, p) % p; if (tyl) { a = (pot(2, p, n) + p - a) % p; } printf("%d\n", a); return 0; } |