codevs3044 线段树+扫描线

3044 矩形面积求并

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// #pragma comment(linker, "/STACK:1024000000,1024000000")
#include <iostream>
#include <cstdio>
#include <cstring>
#include <sstream>
#include <string>
#include <algorithm>
#include <list>
#include <map>
#include <vector>
#include <queue>
#include <stack>
#include <cmath>
#include <cstdlib>
// #include <conio.h>
using namespace std;
#define clc(a,b) memset(a,b,sizeof(a))
#define inf 0x3f3f3f3f
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
const int N = 1100;
const int MOD = 1e9+7;
#define LL long long
#define mi() (l+r)>>1
double const pi = acos(-1);

// inline int r() {
//     int x=0,f=1;char ch=getchar();
//     while(ch>'9'||ch<'0') {if(ch=='-') f=-1;ch=getchar();}
//     while(ch>='0'&&ch<='9') { x=x*10+ch-'0';ch=getchar();}return x*f;
// }
int n;
double hashh[N<<2];
double sum[N<<2];
int color[N<<2];
struct Edge{
     double x1,x2,y;
     int flag;
     bool operator < (const Edge &a) const{
         return y<a.y;
     }
}e[N<<2];

int b_s(double x){
     int l=1,r=2*n;
     int mid;
     while(l<=r){
          mid=(l+r)>>1;
          if(hashh[mid]==x) return mid;
          else if(hashh[mid]<x) l=mid+1;
          else r=mid-1;
     }
}

void pushdown(int rt,int l,int r){
     if(color[rt]) sum[rt]=hashh[r+1]-hashh[l];
     else if(l==r) sum[rt]=0;
     else sum[rt]=sum[rt<<1]+sum[rt<<1|1];
}

void update(int l,int r,int rt,int x,int y,int f){
     if(x==l&&y==r){
          color[rt]+=f;
          pushdown(rt,l,r);
          return;
     }
     int mid=mi();
     if(y<=mid) update(l,mid,rt<<1,x,y,f);
     else if(x>mid) update(mid+1,r,rt<<1|1,x,y,f);
     else {
         update(l,mid,rt<<1,x,mid,f);
         update(mid+1,r,rt<<1|1,mid+1,y,f);
     }
     pushdown(rt,l,r);
}
int main(){
     // int n;
     while(scanf("%d",&n)){
         if(n==0)
            break;
         clc(color,0);
         clc(sum,0); 
         double x1,x2,y1,y2;
         for(int i=1;i<=n;i++){
             scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
             e[i*2-1].x1=e[i*2].x1=x1;
             e[i*2-1].x2=e[i*2].x2=x2;
             e[i*2-1].y=y1;e[i*2].y=y2;
             e[i*2-1].flag=1;e[i*2].flag=-1;
             hashh[i*2-1]=x1;hashh[i*2]=x2;
         }
         sort(e+1,e+1+2*n);
         sort(hashh+1,hashh+1+2*n);
         double ans=0;
         for(int i=1;i<=2*n;i++){
             int l=b_s(e[i].x1),r=b_s(e[i].x2)-1;
             // cout<<"l:"<<l<<" "<<"r:"<<r<<endl;
             if(l<=r) update(1,2*n,1,l,r,e[i].flag);
             // cout<<"sum[1]"<<sum[1]<<endl;
             ans+=sum[1]*(e[i+1].y-e[i].y);
         }
         printf("%.2f
",ans);
     }
     return 0;
}