Line Segment tree + scanning line + discrete solution poj1151 HDU 1542 (Atlanta)

Inspired by this link, we can understand the scanning line:

Http://www.cnblogs.com/scau20110726/archive/2013/04/12/3016765.html

My code is as follows:

#include<iostream>#include<map>#include<string>#include<cstring>#include<cstdio>#include<cstdlib>#include<cmath>#include<queue>#include<vector>#include<algorithm>using namespace std;typedef pair<double,double> ll;vector<double>x;int n;struct node{double l,r,y;int flag;}seg[201];struct node1{int l,r,m;double y;int flag;}tree[801];bool cmp(double a,double b){return a<b;}bool cmp1(node a,node b){return a.y<b.y;}void create(int l,int r,int k){tree[k].l=l;tree[k].r=r;tree[k].m=(l+r)>>1;tree[k].flag=0;if(l+1==r)return;create(l,tree[k].m,k<<1);create(tree[k].m,r,k<<1|1);}void join(int l,int r,int flag,int k){if(tree[k].l==l&&tree[k].r==r){tree[k].flag+=flag;return;}if(r<=tree[k].m)join(l,r,flag,k<<1);else if(l>=tree[k].m)join(l,r,flag,k<<1|1);else{join(l,tree[k].m,flag,k<<1);join(tree[k].m,r,flag,k<<1|1);}}double find(int k){if(tree[k].flag>0)return x[tree[k].r]-x[tree[k].l];if(tree[k].l+1==tree[k].r)return 0;return find(k<<1)+find(k<<1|1);}void in(){ll t1,t2;int i=0;x.clear();while(n--){cin>>t1.first>>t1.second>>t2.first>>t2.second;seg[i].l=t1.first;seg[i].r=t2.first;seg[i].y=t1.second;seg[i].flag=1;x.push_back(t1.first);i++;seg[i].l=t1.first;seg[i].r=t2.first;seg[i].y=t2.second;seg[i].flag=-1;x.push_back(t2.first);i++;}n=i;sort(x.begin(),x.end(),cmp);x.erase(unique(x.begin(),x.end()),x.end());create(0,n-1,1);}double work(){double ans=0,t1;int i,l,r;sort(seg,seg+n,cmp1);n--;for(i=0;i<n;i++){l=lower_bound(x.begin(),x.end(),seg[i].l)-x.begin();r=lower_bound(x.begin(),x.end(),seg[i].r)-x.begin();join(l,r,seg[i].flag,1);t1=find(1);ans+=find(1)*(seg[i+1].y-seg[i].y);}return ans;}int main(){int jishu=0;while(cin>>n&&n!=0){in();printf("Test case #%d\nTotal explored area: %.2lf\n\n",++jishu,work());}}