bzoj1407

直接枚举山洞的数量，对每个值枚举点对解同余方程判断即可

好久没写辣结果狂wa不止qaq

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<cstring>
using namespace std;
typedef long long LL;
inline int read()
{
	int x=0;bool f=0;char c=getchar();
	for (;c<'0'||c>'9';c=getchar()) f=c=='-'?1:0;
	for (;c>='0'&&c<='9';c=getchar()) x=x*10+c-'0';
	return f?-x:x;
}
const int N=1000000;
int n,ma,C[20],P[20],L[20],k,l,g,r2;

void exgcd(int x,int y)
{
	if (!y) {k=1,l=0,g=x;return;}
	exgcd(y,x%y);
	r2=l;l=k-l*(x/y);k=r2;
}

int main()
{

	n=read();

	for (int i=1;i<=n;i++)
		ma=max(ma,C[i]=read()),P[i]=read(),L[i]=read();
	for (int m=ma,da,db,mm,t;m<=N;m++)
	{
		bool ok=1;
		for (int i=1;i<=n&&ok;i++)
			for (int j=i+1;j<=n;j++)
			{
				da=(P[j]-P[i]+m)%m;db=(C[i]-C[j]+m)%m;
				exgcd(m,da);
				if (db%g) continue;
				db/=g;mm=m/g;
				t=(LL)l*db%mm;
				if (t<0) t+=mm;
				if (t<=L[i]&&t<=L[j]) {ok=0;break;}
			}
		if (ok) {printf("%d\n",m);break;}
	}
	return 0;
}