POJ1151(矩形切割入门题)

题目：Atlantis

我的上一篇文章已经讲明了线段切割的思想，矩形切割就是把线段切割从一维推到二维就行了，思想都一样。

#include <stdio.h>
#include <string.h>

const int N = 205;

typedef struct
{
    double x1,y1;
    double x2,y2;
    double sum;
}Node;

Node T[N];

int n;

void Cover(double x1,double y1,double x2,double y2,int k,int c)
{
    while(k<n&&(x1>=T[k].x2||x2<=T[k].x1||y1>=T[k].y2||y2<=T[k].y1)) k++;
    if(k>=n)
    {
        T[c].sum+=(x2-x1)*(y2-y1);
        return;
    }
    if(x1<T[k].x1)
    {
        Cover(x1,y1,T[k].x1,y2,k+1,c);
        x1=T[k].x1;
    }
    if(x2>T[k].x2)
    {
        Cover(T[k].x2,y1,x2,y2,k+1,c);
        x2=T[k].x2;
    }
    if(y1<T[k].y1)
    {
        Cover(x1,y1,x2,T[k].y1,k+1,c);
        y1=T[k].y1;
    }
    if(y2>T[k].y2)
    {
        Cover(x1,T[k].y2,x2,y2,k+1,c);
        y2=T[k].y2;
    }
}

int main()
{
    int i,k=1;
    while(~scanf("%d",&n),n)
    {
        for(i=0;i<n;i++)
        {
            scanf("%lf%lf%lf%lf",&T[i].x1,&T[i].y1,&T[i].x2,&T[i].y2);
            T[i].sum=0;
        }
        for(i=n-1;i>=0;i--)
            Cover(T[i].x1,T[i].y1,T[i].x2,T[i].y2,i+1,i);
        double ans=0;
        for(i=0;i<n;i++)
           ans+=T[i].sum;
        printf("Test case #%d\n",k++);
        printf("Total explored area: %.2lf\n\n",ans);
    }
    return 0;
}