G20 扩展中国剩余定理

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
void exgcd(LL a, LL b, LL &d, LL &x, LL &y) 
{
    if(b == 0) d = a, x = 1, y = 0;
    else
    {
        exgcd(b, a % b, d, y, x);
        y -= (a / b) * x;
    }
}
int main()
{
    LL a1, b1, a2, b2, A, B, X, Y, K, d;
    int n; scanf("%d", &n);
    bool bk = true;
    scanf("%lld%lld", &a1, &b1);
    for(int i = 2; i <= n; i++) 
    {
        scanf("%lld%lld", &a2, &b2);
        A = a1; B = a2; K = b2 - b1;
        exgcd(A, B, d, X, Y);
        if(K % d != 0) bk = false;
        LL dx = abs(B / d), dy = abs(A / d);
        X = X * (K / d);
        X = (X % dx + dx) % dx;
        b1 = a1 * X + b1;
        a1 = a1 / d * a2;
    }
    if(bk == false) printf("no solution!\n");
    else printf("%lld\n", b1);
    return 0;
}

中国剩余定理 求同余方程组