POJ1151Atlantis（离散化求矩形面积并）

#include 
#include <string.h>
#include 
#define N 110
int n;
double xl[N],yl[N];
double xr[N],yu[N];
double x[2*N],y[2*N];
int xcnt,ycnt;
bool flag[2*N][2*N];

int cmp(const void *a,const void *b)
{
    return *(double*)a>*(double*)b?1:-1;
}
void init()
{
    xcnt=ycnt=0;
    memset(flag,0,sizeof(flag));
}
void read()
{
    double a,b,c,d;
    for(int i=0;i)
    {
        scanf("%lf%lf%lf%lf",&a,&b,&c,&d);
        xl[i]=a;    yl[i]=b;
        xr[i]=c;    yu[i]=d;

        x[xcnt++]=a;    x[xcnt++]=c;
        y[ycnt++]=b;    y[ycnt++]=d;
    }
}
int bsx(double k)
{
    int min=0,max=xcnt,mid;
    while(min+1!=max)
    {
        mid=min+max>>1;
        if(x[mid]>k)    max=mid;
        else    min=mid;
    }
    return min;
}
int bsy(double k)
{
    int min=0,max=ycnt,mid;
    while(min+1!=max)
    {
        mid=min+max>>1;
        if(y[mid]>k)    max=mid;
        else    min=mid;
    }
    return min;
}
void solve()
{
    int i,j,k;
    qsort(x,xcnt,sizeof(x[0]),cmp);
    qsort(y,ycnt,sizeof(y[0]),cmp);

    k=xcnt;
    xcnt=0;
    x[xcnt++]=x[0];
    for(i=1;iif(x[xcnt-1]!=x[i])  x[xcnt++]=x[i];


    k=ycnt;
    ycnt=0;
    y[ycnt++]=y[0];
    for(i=1;iif(y[ycnt-1]!=y[i])  y[ycnt++]=y[i];

    int a,b,c,d;
    for(k=0;k)
    {
        a=bsx(xl[k]);    b=bsy(yl[k]);
        c=bsx(xr[k]);    d=bsy(yu[k]);
        for(i=a;i)
        {
            for(j=b;jtrue;
        }
    }
    double ans=0;
    for(i=0;i1;i++)
    {
        for(j=0;j1;j++)   if(flag[i][j])  ans+=(x[i+1]-x[i])*(y[j+1]-y[j]);
    }
    printf("Total explored area: %.2lf\n\n",ans);
}
int main()
{
    int kase=0;
    while(scanf("%d",&n),n)
    {
        init();
        read();
        printf("Test case #%d\n",++kase);
        solve();
    }
    return 0;
}