noip模拟赛 同余方程组

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;

ll mod[5], a[5], gcd, lcm, ans;

ll GCD(ll x, ll y)
{
    if (!y)
        return x;
    return GCD(y, x % y);
}

int main()
{
    scanf("%lld%lld%lld%lld%lld%lld%lld%lld", &mod[1], &a[1], &mod[2], &a[2], &mod[3], &a[3], &mod[4], &a[4]);
    lcm = mod[1];
    gcd = mod[1];
    ans = a[1];
    for (int i = 2; i <= 4; i++)
    {
        while (ans % mod[i] != a[i])
            ans += lcm;
        gcd = GCD(gcd, mod[i]);
        lcm = lcm / gcd * mod[i];
    }
    printf("%lld\n", ans);

    return 0;
}