OJ-Problems-Source/HDOJ/5490_autoAC.cpp

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#include <iostream>
#include <cstdio>
#include <cstdlib>
#define LL long long
#define MOD 1000000007
using namespace std;
LL b1, q, a1, d, n, m;
LL ans, dis[10005];
void input()
{
ans = 0;
scanf("%I64d%I64d%I64d%I64d%I64d%I64d", &b1, &q, &a1, &d, &n, &m);
}
void exgcd(LL a, LL b, LL &x, LL &y, LL &d)
{
if (b == 0)
{
x = 1;
y = 0;
d = a;
}
else
{
exgcd(b, a%b, y, x, d);
y -= a/b*x;
}
}
LL modDiv(LL a, LL b)
{
LL x, y, d;
exgcd(b, MOD, x, y, d);
x = (x+MOD) % MOD;
x = (x*a/d) % MOD;
return x;
}
LL quickPow(LL x, LL n)
{
LL a = 1;
while (n)
{
a *= n&1 ? x : 1;
a %= MOD;
n >>= 1 ;
x *= x;
x %= MOD;
}
return a;
}
void work()
{
LL now = b1, tmp;
now %= MOD;
for (int i = 1; i <= n; ++i)
{
tmp = modDiv(now, q-1);
now = now+tmp;
now %= MOD;
dis[i] = (a1+(i-1)*d%MOD-tmp)%MOD;
dis[i] = (dis[i]+MOD)%MOD;
}
LL qt = 1;
ans += qt*dis[n];
for (int i = n-1; i > 0; --i)
{
qt = modDiv((qt*((n+m-1)-i)%MOD+MOD)%MOD, n-i);
ans += (qt*dis[i])%MOD;
ans %= MOD;
}
tmp = quickPow(q, (m-1)%(MOD-1))%MOD;
ans += now*tmp%MOD;
ans %= MOD;
printf("%I64d\n", ans);
}
int main()
{
int T;
scanf("%d", &T);
for (int times = 1; times <= T; ++times)
{
printf("Case #%d: ", times);
input();
work();
}
return 0;
}