#include <cstdio> #include "message.h" #include "futbol.h" #define ll long long ll p; ll pow(ll a, ll b) { ll x = 1; a %= p; while(b > 0) { if((b&1)!=0) { x *= a; x %= p; } b >>= 1; a *= a; a %= p; } return x; } ll div(ll a, ll b) { return (a*pow(b,p-2))%p; } int* inv; void makeInv() { inv = new int[p+5]; inv[1] = 1; for(int i=2;i<p;i++) { inv[i] = (p - ((p/i)*inv[p%i] % p)) % p; } } int main(int argc, char** argv) { int me = MyNodeId(); if(me == 0) { ll n = GetN(); ll k = GetK(); if(k > n/2) { k = n-k; } p = GetP(); ll res = 1; ll num = 1; ll den = 1; if(p < 14000000) { makeInv(); for(ll i=1;i<=k;i++) { num *= n+1-i; num %= p; den *= i; den %= p; ll a = num * inv[den]; a %= p; res += a; res %= p; } } else { for(ll i=1;i<=k;i++) { num *= n+1-i; num %= p; den *= i; den %= p; res += div(num,den); res %= p; } } printf("%lld\n", res); } 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 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | #include <cstdio> #include "message.h" #include "futbol.h" #define ll long long ll p; ll pow(ll a, ll b) { ll x = 1; a %= p; while(b > 0) { if((b&1)!=0) { x *= a; x %= p; } b >>= 1; a *= a; a %= p; } return x; } ll div(ll a, ll b) { return (a*pow(b,p-2))%p; } int* inv; void makeInv() { inv = new int[p+5]; inv[1] = 1; for(int i=2;i<p;i++) { inv[i] = (p - ((p/i)*inv[p%i] % p)) % p; } } int main(int argc, char** argv) { int me = MyNodeId(); if(me == 0) { ll n = GetN(); ll k = GetK(); if(k > n/2) { k = n-k; } p = GetP(); ll res = 1; ll num = 1; ll den = 1; if(p < 14000000) { makeInv(); for(ll i=1;i<=k;i++) { num *= n+1-i; num %= p; den *= i; den %= p; ll a = num * inv[den]; a %= p; res += a; res %= p; } } else { for(ll i=1;i<=k;i++) { num *= n+1-i; num %= p; den *= i; den %= p; res += div(num,den); res %= p; } } printf("%lld\n", res); } return 0; } |