poj 1006 中国剩余定理

用exgcd求逆元,数据很水,int不会爆

#include<iostream>#include<cstdio>#include<cmath>#include<cstring>#include<algorithm>#define fo(i,a,b) for(int i=a;i<=b;i++)#define fod(i,a,b) for(int i=a;i>=b;i--)using namespace std;int m[4],a[4],p,e,i;void exgcd(int a,int b,int &d,int &x,int &y){    if(b==0){d=a;x=1;y=0;return ;}    exgcd(b,a%b,d,x,y);    int t=x;x=y;y=t-(a/b)*y; }int getinv(int a,int mod) {    int x,y,d;     exgcd(a,mod,d,x,y);    if(d==1) return (x%mod+mod)%mod;    else return -1;}int crt(){    int M=1,ans=0;    fo(i,1,3) M*=m[i];    for(int i=1;i<=3;i++) {        int Mi=M/m[i];        ans=(ans+Mi*getinv(Mi,m[i])*a[i])%M;    }    return ans<0?ans+M:ans;}int main(){    int kase=0,d;    while(scanf("%d%d%d%d",&p,&e,&i,&d))    {        if(p==e&&e==i&&i==d&&d==-1) break;        a[1]=p;a[2]=e;a[3]=i;        m[1]=23;m[2]=28;m[3]=33;        int ans=crt(); if(ans<=d) ans+=21252;         printf("Case %d: the next triple peak occurs in %d days.\n",++kase,ans-d);    }    return 0;}