poj 1389

求矩形的面积并

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
const int maxn=1101;
int ans;
struct
{
    int l,r,x;
    int y1,y2;
    bool ture;
    int count;
}tr[10000];

struct data
{
    int x,y1,y2,count;
    bool operator <(const data &xx) const
    {
        return(x<xx.x);
    }
}d[maxn*2];
int y[maxn*2];

int maketree(int t,int l,int r)
{
    tr[t].l=l;
    tr[t].r=r;
    tr[t].y1=y[l];
    tr[t].y2=y[r];
    tr[t].ture=1;
    tr[t].count=0;
    if(l+1==r)
    return(0);
    int mid=(l+r)/2;
    maketree(t*2,l,mid);
    maketree(t*2+1,mid,r);
}

int pushdown(int t)
{
    tr[t*2].x=tr[t].x;
    tr[t*2].count=tr[t].count;
    tr[t*2+1].x=tr[t].x;
    tr[t*2+1].count=tr[t].count;
}

int insert(int t,int y1,int y2,data &d)
{
    if(tr[t].y1==y1&&tr[t].y2==y2)
    {
        if(tr[t].ture)
        {
            if(tr[t].count>0)
            {
                int txt=y2-y1;
                ans+=txt*(d.x-tr[t].x);
            }
            tr[t].count+=d.count;
            tr[t].x=d.x;
            return(0);
        }
    }
    if(tr[t].ture)
    pushdown(t);
    tr[t].ture=0;
    int mid=(tr[t].l+tr[t].r)/2;
    mid=y[mid];
            if(mid<=y1)
            insert(t*2+1,y1,y2,d);
            else if(y2<=mid)
            insert(t*2,y1,y2,d);
            else
            {
                insert(t*2,y1,mid,d);
                insert(t*2+1,mid,y2,d);
            }
}



int main()
{
    int n;
    while(1)
    {
        int x1,x2,y1,y2;
        scanf("%d %d %d %d",&x1,&y1,&x2,&y2);
        if(x1==-1&&y1==-1&&x2==-1&&y2==-1)
        break;
        d[1].x=x1;
        d[1].y1=y1;
        d[1].y2=y2;
        d[2].x=x2;
        d[2].y1=y1;
        d[2].y2=y2;
        d[1].count=1;
        d[2].count=-1;
        y[1]=y1;
        y[2]=y2;
        for(int i=2;;i++)
        {
            scanf("%d %d %d %d",&x1,&y1,&x2,&y2);
            int now=2*i-1,next=now+1;
            d[now].x=x1;
            d[now].y1=y1;
            d[now].y2=y2;
            d[next].x=x2;
            d[next].y1=y1;
            d[next].y2=y2;
            d[now].count=1;
            d[next].count=-1;
            y[now]=y1;
            y[next]=y2;
            if(x1==-1&&y1==-1&&x2==-1&&y2==-1)
            {
                n=i-1;
                break;
            }
        }
        sort(y+1,y+2*n+1);
        sort(d+1,d+2*n+1);
        maketree(1,1,2*n);
        ans=0;
        for(int i=1;i<=2*n;i++)
        {
            insert(1,d[i].y1,d[i].y2,d[i]);
//            printf("%d %d\n",d[i].x,ans);
        }
        printf("%d\n",ans);
    }
    return 0;
}