CCPC-Wannafly Camp #4（部分解題報告）

B: 電音之王

時間限制: 7 Sec  內存限制: 1024 MB

第一次據說快速乘法，記錄一下，用的大佬的板子

#include<bits/stdc++.h>
#define LL long long
using namespace std;

LL multi(LL x,LL y,LL mod){
    LL tmp = (x * y - (LL)((long double) x / mod * y + 1.0e-8) * mod);
    return tmp < 0 ? tmp+mod : tmp;
}
/// an = m0an−1 + m1an−2 + c
int main()
{
    int T;
    scanf("%d",&T);
    while(T--){
        LL a0, a1, m0, m1, c, M, k;
        scanf("%lld%lld%lld%lld%lld%lld%lld", &a0, &a1, &m0, &m1, &c, &M, &k);
        LL ans = 0;
        ans += multi(a0, a1, M);
        for(int i = 2; i <= k; i++) {
            LL p1 = multi(m0, a1, M);
            LL p0 = multi(m1, a0, M);
            LL t = p1 + p0 + c;
            ans = multi(t, ans, M);
            a0 = a1;
            a1 = t;
        }
        printf("%lld\n", ans);
    }
    return 0;
}