HDU 1147 Pick-up sticks 线段判交。暴搜
2011-08-28 00:36
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//其实刚遇到这道题目的时候是会做的,,但是却找不到线段相交的模板实在让我无语。。
//意识到模板的重要性了。。
/***********************************
暴力就行,从第一个开始判断
如果两条线段相交就把前面一条筛选掉
判断线段相交直接贴的吉大模板。。。
***********************************/
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int maxn=100000+5;
const double eps=1e-10;
struct point
{
double x,y;
};
point p[maxn],b[maxn];
bool ans[maxn];
double min(double a,double b)
{
return a< b?a:b;
}
double max(double a, double b)
{
return a>b?a:b;
}
bool inter(point a,point b,point c,point d)
{
if( min(a.x, b.x)>max(c.x,d.x)||
min(a.y, b.y)>max(c.y,d.y)||
min(c.x, d.x)>max(a.x,b.x)||
min(c.y, d.y)>max(a.y, b.y) )
return 0;
double h,i,j,k;
h=(b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);
i=(b.x-a.x)*(d.y-a.y)-(b.y-a.y)*(d.x-a.x);
j=(d.x-c.x)*(a.y-c.y)-(d.y-c.y)*(a.x-c.x);
k=(d.x-c.x)*(b.y-c.y)-(d.y-c.y)*(b.x-c.x);
return h*i<=eps&&j*k<=eps;
}
int main()
{
int n,i,j;
int res[maxn];
while(cin>>n,n)
{
memset(ans,0,sizeof(ans));
for(i=0; i<n; i++ )
{
cin>>p[i].x>>p[i].y>>b[i].x>>b[i].y;
}
for(i=0; i<n; i++ )
{
for(j=i+1;j<n;j++)
{
if(inter(p[i],b[i],p[j],b[j]) )
{
ans[i]=1;
break; //不加break会超时。。。
}
}
}
int ct=0;
cout<< "Top sticks: ";
for(i=0; i<n; i++ )
if(!ans[i])
res[ct++]=i+1;
for(i=0; i<ct-1; i++ )
cout<<res[i]<<", ";
cout<<res[ct-1]<<"."<<endl;
}
return 0;
}
//意识到模板的重要性了。。
/***********************************
暴力就行,从第一个开始判断
如果两条线段相交就把前面一条筛选掉
判断线段相交直接贴的吉大模板。。。
***********************************/
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int maxn=100000+5;
const double eps=1e-10;
struct point
{
double x,y;
};
point p[maxn],b[maxn];
bool ans[maxn];
double min(double a,double b)
{
return a< b?a:b;
}
double max(double a, double b)
{
return a>b?a:b;
}
bool inter(point a,point b,point c,point d)
{
if( min(a.x, b.x)>max(c.x,d.x)||
min(a.y, b.y)>max(c.y,d.y)||
min(c.x, d.x)>max(a.x,b.x)||
min(c.y, d.y)>max(a.y, b.y) )
return 0;
double h,i,j,k;
h=(b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);
i=(b.x-a.x)*(d.y-a.y)-(b.y-a.y)*(d.x-a.x);
j=(d.x-c.x)*(a.y-c.y)-(d.y-c.y)*(a.x-c.x);
k=(d.x-c.x)*(b.y-c.y)-(d.y-c.y)*(b.x-c.x);
return h*i<=eps&&j*k<=eps;
}
int main()
{
int n,i,j;
int res[maxn];
while(cin>>n,n)
{
memset(ans,0,sizeof(ans));
for(i=0; i<n; i++ )
{
cin>>p[i].x>>p[i].y>>b[i].x>>b[i].y;
}
for(i=0; i<n; i++ )
{
for(j=i+1;j<n;j++)
{
if(inter(p[i],b[i],p[j],b[j]) )
{
ans[i]=1;
break; //不加break会超时。。。
}
}
}
int ct=0;
cout<< "Top sticks: ";
for(i=0; i<n; i++ )
if(!ans[i])
res[ct++]=i+1;
for(i=0; i<ct-1; i++ )
cout<<res[i]<<", ";
cout<<res[ct-1]<<"."<<endl;
}
return 0;
}
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