城市地平线

 1 #include"iostream"
 2 #include"cstdio"
 3 #include"cstring"
 4 #include"algorithm"
 5 using namespace std;
 6 const int ms=50001;
 7 typedef long long LL;
 8 struct building
 9 {
10     LL l,r,h;
11 }line[ms];
12 LL node[ms*2];
13 struct tree
14 {
15     LL l,r,h;
16 }treenode[ms*4];
17 bool cmp(const building &a,const building &b)
18 {
19     return a.h<b.h;
20 }
21 void init(int n);
22 void build(LL l,LL r,int p);
23 void insert(LL l,LL r,LL value,int p);
24 LL search(int p);
25 int main()
26 {
27     int n;
28     scanf("%d",&n);
29     init(n);
30     build(1,node[0],1);
31     for(int i=1;i<=n;i++)
32         insert(line[i].l,line[i].r,line[i].h,1);
33     printf("%I64d\n",search(1));
34     return 0;
35 }
36 void init(int n)
37 {
38     memset(treenode,0,sizeof(treenode));
39     memset(node,0,sizeof(node));
40     memset(line,0,sizeof(line));
41     for(int i=1;i<=n;i++)
42     {
43         scanf("%I64d%I64d%I64d",&line[i].l,&line[i].r,&line[i].h);
44         node[i*2-1]=line[i].l;
45         node[i*2]=line[i].r;
46     }
47     sort(line+1,line+1+n,cmp);
48     int j=1;
49     sort(node+1,node+2*n+1);
50     for(int i=1;i<=2*n;i++)
51     {
52         if(node[i]!=node[j])
53             node[++j]=node[i];
54     }
55     node[0]=j;
56     return ;
57 }
58 void build(LL l,LL r,int p)
59 {
60     treenode[p].l=node[l];
61     treenode[p].r=node[r];
62     //cout<<p<<" : "<<node[l]<<" : "<<node[r]<<endl;
63     if(l+1==r)
64         return ;
65     int mid=(l+r)/2;
66     build(l,mid,2*p);
67     build(mid,r,2*p+1);
68     return ;
69 }
70 void insert(LL l,LL r,LL value,int p)
71 {
72     if(l<=treenode[p].l&&treenode[p].r<=r)
73     {
74         treenode[p].h=value;
75         return ;
76     }
77     if(treenode[p].h>0)
78         treenode[p*2].h=treenode[2*p+1].h=treenode[p].h;
79     treenode[p].h=-1;
80     if(r>treenode[2*p].r)
81         insert(l,r,value,p*2+1);
82     if(l<treenode[2*p].r)
83         insert(l,r,value,2*p);
84     return ;
85 }
86 LL search(int p)
87 {
88     if(treenode[p].h>0)
89         return treenode[p].h*(treenode[p].r-treenode[p].l);
90     if(treenode[p].h==0)
91         return 0;
92     return (search(2*p)+search(2*p+1));
93 }