中國剩餘定理，求解符合若干個x%a[i]≡b[i]的答案x（模板中求出的最小的非負整數解）

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int a[3],b[3]={23,28,33};
void exgcd(int a,int b,int &x,int &y)
{
    if(b==0)
    { 
        x=1;y=0; 
        return;
    }
    exgcd(b,a%b,x,y);
    
 
int tmp=x;
    x=y; 
    y=tmp-a/b*y;
}
int crt(int n)
{
    int i,tmp,ans=0,lcm=1,x,y;
    for (i=0;i<n;++i) lcm*=b[i];
    for (i=0;i<n;++i)
    {
        tmp=lcm/b[i];
        exgcd(tmp,b[i],x,y);
        x=(x%b[i]+b[i])%b[i];
        ans=(ans+tmp*x*a[i])%lcm;
    }
    return (ans+lcm)%lcm;
}
int
 
 main()
{
    int p,e,i,d;
    int cnt=0,ans;
    while (scanf("%d%d%d%d",&p,&e,&i,&d)!=EOF)
    {
        if (p==-1) break;
        a[0]=p;
        a[1]=e;
        a[2]=i;
        ans=crt(3);
        if (ans<=d) ans+=21252;
        cnt++;
        printf("Case %d: the next triple peak occurs in %d days.\n
 
",cnt,ans-d);
    } 
    return 0;
}