poj 1151 线段树+扫描线

/**************************************************************
Problem:poj 1151
User: youmi
Language: C++
Result: Accepted
Time:0MS
Memory:740K
****************************************************************/
//#pragma comment(linker, "/STACK:1024000000,1024000000")
//#include<bits/stdc++.h>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <map>
#include <stack>
#include <set>
#include <sstream>
#include <cmath>
#include <queue>
#include <deque>
#include <string>
#include <vector>
#define zeros(a) memset(a,0,sizeof(a))
#define ones(a) memset(a,-1,sizeof(a))
#define sc(a) scanf("%d",&a)
#define sc2(a,b) scanf("%d%d",&a,&b)
#define sc3(a,b,c) scanf("%d%d%d",&a,&b,&c)
#define scs(a) scanf("%s",a)
#define sclld(a) scanf("%I64d",&a)
#define pt(a) printf("%d\n",a)
#define ptlld(a) printf("%I64d\n",a)
#define rep0(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define rep_1(i,n) for(int i=n;i>=1;i--)
#define rep_0(i,n) for(int i=n-1;i>=0;i--)
#define Max(a,b) ((a)>(b)?(a):(b))
#define Min(a,b) ((a)<(b)?(a):(b))
#define lson (step<<1)
#define rson (lson+1)
#define esp 1e-6
#define oo 0x3fffffff
#define TEST cout<<"*************************"<<endl

using namespace std;
typedef long long ll;

int n;
const int maxn=1000;
double x[maxn];
struct node
{
double xl,xr,y,s;
node(){}
node(double _xl,double _xr,double _y,double _s)
{
xl=_xl,xr=_xr,y=_y,s=_s;
}
bool operator<(const node & b)const
{
return y<b.y;
}
}line[maxn];
struct Seg
{
int l,r,flag;
double sum;
Seg(){}
Seg(int _l,int _r,int _flag,double _sum)
{
l=_l,r=_r,flag=_flag,sum=_sum;
}
}seg[maxn];
int sgn(double x0)
{
if(fabs(x0)<esp)
return 0;
if(x0<0)
return -1;
else
return 1;
}
int bs(double x0)
{
int l=1,r=n;
while(l<=r)
{
int mid=(l+r)>>1;
if(sgn(x0-x[mid])==0)
return mid;
if(sgn(x0-x[mid])==1)
l=mid+1;
else
r=mid-1;
}
}
void pushup(int step)
{
if(seg[step].flag)
seg[step].sum=x[seg[step].r+1]-x[seg[step].l];
else if(seg[step].l==seg[step].r)
seg[step].sum=0;
else
seg[step].sum=seg[lson].sum+seg[rson].sum;
}
void build(int step,int l,int r)
{
seg[step]=Seg(l,r,0,0);
if(l==r)
return ;
int mid=(l+r)>>1;
build(lson,l,mid);
build(rson,mid+1,r);
}
void update(int step,int l,int r,int val)
{
if(seg[step].l==l&&seg[step].r==r)
{
seg[step].flag+=val;
pushup(step);
return;
}
int mid=(seg[step].l+seg[step].r)>>1;
if(mid>=r)
update(lson,l,r,val);
else if(mid<l)
update(rson,l,r,val);
else
{
update(lson,l,mid,val);
update(rson,mid+1,r,val);
}
pushup(step);
}
int main()
{
//freopen("in.txt","r",stdin);
int kase=0;
while(~sc(n)&&n)
{
if(kase)
cout<<endl;
double x1,y1,x2,y2;
int cnt=0;
for(int i=1;i<=n;i++)
{
scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
line[cnt++]=node(x1,x2,y1,1);
x[cnt]=x1;
line[cnt++]=node(x1,x2,y2,-1);
x[cnt]=x2;
}
sort(x+1,x+cnt+1);
sort(line,line+cnt);
n=1;
for(int i=2;i<=cnt;i++)
if(x[i]!=x[i-1])
x[++n]=x[i];
build(1,1,n);
double ans=0;
for(int i=0;i<cnt-1;i++)
{
int l=bs(line[i].xl);
int r=bs(line[i].xr)-1;
update(1,l,r,line[i].s);
ans+=seg[1].sum*(line[i+1].y-line[i].y);
}
printf("Test case #%d\n",++kase);
printf("Total explored area: %.2f \n",ans);
}
return 0;
}