|poj 1006|中国剩余定理|Biorhythms

poj传送门
裸的中国剩余定理，注意一下负数的情况即可

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