4/18 数学+思维

Posted 2022-04-21 钟钟终

P1495 【模板】中国剩余定理(CRT)/曹冲养猪
一定别忘记加引用！！服了

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N=1e5+5;
ll n,a[15],b[15];
ll ex_gcd(ll a,ll b,ll &x,ll &y)

    if(b==0)
    
        x=1,y=0;return a;
    
    ll d=ex_gcd(b,a%b,x,y);
    ll tmp=x;
    x=y;
    y=tmp-(a/b)*y;
    return d;

ll ex_crt()

    ll aa=b[1],rr=a[1],x,y;
    for(int i=2;i<=n;i++)
    
        ll bb=b[i];
        ll c=a[i]-rr;
        ll d=ex_gcd(aa,bb,x,y);
        if(c%d) return -1;
        c=c/d;bb=bb/d;
        x=(x*c%bb+bb)%bb;
        ll lcm=aa*bb;
        rr=(x*aa%lcm+rr)%lcm;
        aa=lcm;
    
    return rr;


signed main()

    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>b[i]>>a[i];
    cout<<ex_crt()<<endl;
    return 0;