ACM基础训练题解4301 城市地平线

 1 //城市地平线(线段树)
 2 #include<iostream>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<cstdio>
 7 using namespace std;
 8 typedef __int64 LL;
 9 struct building{
10     LL x1;
11     LL x2;
12     LL height;
13 }line[50000];
14 LL node[100000];
15 struct tree{
16     LL left;
17     LL right;
18     LL hi;
19 }treenode[1000000];
20 bool cmp(building a,building b){
21     return (a.height<b.height );
22 }
23 void clear(int n){
24     memset(treenode,0,sizeof(treenode));
25     memset(node,0,sizeof(node));
26     memset(line,0,sizeof(line));
27     for(int i=1;i<=n;i++){
28         cin>>line[i].x1>>line[i].x2>>line[i].height;
29         node[i*2-1]=line[i].x1;
30         node[i*2]=line[i].x2;
31     }
32     sort(line+1,line+n+1,cmp);
33     int j=1;
34     sort(node+1,node+1+2*n);
35     for(int i=1;i<=n*2;i++){
36         if(node[j]!=node[i])
37          node[++j]=node[i];
38     }
39     node[0]=j;
40     return ;
41 }
42 void creatree(int ll,int rr,int p){
43     treenode[p].left=node[ll];
44     treenode[p].right=node[rr];
45     if(ll+1==rr)
46       return ;
47     int mid=(ll+rr)/2;
48     creatree(ll,mid,p*2);
49     creatree(mid,rr,p*2+1);//***
50     return ;
51 }
52 void insert(LL ileft,LL iright,LL value,int p){
53     if(ileft<=treenode[p].left && treenode[p].right<=iright){
54         treenode[p].hi=value;
55         return ;
56     }
57     if(treenode[p].hi>0)
58       treenode[p*2].hi=treenode[p*2+1].hi=treenode[p].hi;
59     treenode[p].hi=-1;
60     if(iright>treenode[p*2].right)
61       insert(ileft,iright,value,p*2+1);
62     if(ileft<treenode[p*2].right)
63      insert(ileft,iright,value,p*2);
64     return ;
65 }
66 LL search(int p){
67     if(treenode[p].hi>0)
68       return (treenode[p].hi*(treenode[p].right-treenode[p].left));
69     if(treenode[p].hi==0)
70       return 0;
71     return (search(p*2)+search(p*2+1));
72 }
73 int main(){
74     int n;
75     cin>>n;
76     clear(n);
77     creatree(1,node[0],1);
78     for(int i=1;i<=n;i++)
79       insert(line[i].x1,line[i].x2,line[i].height,1);
80       cout<<search(1)<<endl;
81     return 0;
82 }