19牛客 10 -D Han Xin and His Troops（中國剩餘定理 不互質）

題目鏈接

拓展歐幾里得解線性同餘方程組

#include <iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<queue>
#include<cmath>
using namespace std;
typedef __int128 ll;
ll n,m;
const int maxn=1e5+10;
ll a[maxn],p[maxn];
void read(ll &ret){
    char c;
    while((c=getchar())&&(c>'9'||c<'0'));
    ret=0;
    while(c>='0'&&c<='9') ret=ret*10+c-'0', c=getchar();
}
void out(ll x){
    if(x>9)  out(x/10);
    putchar(x%10+'0');
}
void exgcd(ll a,ll b,ll &d,ll &x,ll &y){
    if(b==0){
        x=1;
        y=0;
        d=a;
    }
    else{
        exgcd(b,a%b,d,y,x);
        y-=x*(a/b);
    }
}
ll excrt(){
    ll M=p[1];
    ll ret=a[1];
    for(int i=2;i<=n;i++){
        ll c=(a[i]-ret%p[i]+p[i])%p[i];
        ll x,y,g;
        exgcd(M,p[i],g,x,y);
        if(c%g!=0)
            return -1; //無解
        ll bg=p[i]/g;
        x=(x%bg)*(c/g%bg)%bg;
        x=(x+p[i])%bg;
        ret+=x*M;
        M*=bg;
    }
    return ret;
}
 
int main(){
     read(n);read(m);
     for(int i=1;i<=n;i++){
          read(p[i]);read(a[i]);
     }
     ll ret = excrt();
     if(ret==-1)
          printf("he was definitely lying");
     else if(ret>m)
          printf("he was probably lying");
     else
          out(ret);
     return 0;
}