C++

$\color{#cc33ff}{— > 算法基础课题解}$

#include<iostream>
#include<algorithm>

using namespace std;

typedef long long ll;

ll exgcd(ll a, ll b, ll &x, ll &y) {
    if (!b) {
        x = 1, y = 0;
        return a;
    }
    ll d = exgcd(b, a % b, y, x);
    y -= a / b * x;
    return d;
}


int main() {
    int n;
    cin >> n;

    bool has_answer = true;
    ll a1, m1;
    cin >> a1 >> m1;
    for (int i = 0; i < n - 1; i ++) {
        ll a2, m2;
        cin >> a2 >> m2;

        ll k1, k2;
        ll d = exgcd(a1, a2, k1, k2);
        if ((m2 - m1) % d) {
            has_answer = false;
            break;
        }

        k1 *= (m2 - m1) / d;
        ll t = a2 / d;
        k1 = (k1 % t + t) % t;
        m1 = a1 * k1 + m1;
        a1 = abs(a1 / d * a2);
    }

    if (has_answer) cout << (m1 % a1 + a1) % a1;
    else cout << -1;
    return 0;
}