Lucas大组合数模板

typedef long long ll;struct Lucas { ll n, m, p; ll qPow (ll a, ll k) { ll ans = 1; while (k) { if (k&1) ans = (ans * a) % p; a = (a * a) % p; k /= 2; } return ans; } ll C (ll a, ll b) { if (a < b) return 0; if (b > a - b) b = a - b; ll up = 1, down = 1; for (ll i = 0; i < b; i++) { up = up * (a-i) % p; down = down * (i+1) % p; } return up * qPow(down, p-2) % p; } ll lucas (ll a, ll b, ll c) { //求C a取b %c （只需调用该函数即可） n=a,m=b,p=c; if (b == 0) return 1; return C(a%p, b%p) * lucas(a/p, b/p, p) % p; }} hehe;