POJ 3277 City Horizon

ZAKIR — Sun, 29 Aug 2010 03:42:00 GMT

  1 #include <iostream>
  2 #include <algorithm>
  3 #include <cstdio>
  4 using namespace std;
  5
  6 const int MaxSize=90001;
  7
  8 struct Node
  9 {    int left,right,mid;
10     int hight;
11 };
12
13
14 struct Building
15 {    int left,right,hight;
16 }b[40001];
17 bool cmp(Building a,Building b)
18 {    return a.hight>b.hight;}
19
20 Node itree[3*MaxSize];
21
22 void Build(int l,int r,int num)
23 {    itree[num].left=l;
24     itree[num].right=r;
25     itree[num].mid=(l+r)/2;
26     itree[num].hight=0;
27
28     if(l+1!=r)
29     {    Build(l,itree[num].mid,num<<1);
30         Build(itree[num].mid,r,(num<<1)+1);
31     }
32 }
33
34 void Insert(int l,int r,int h,int num)
35 {    if(itree[num].left==l&&itree[num].right==r)
36     {    if(h>itree[num].hight)
37             itree[num].hight=h;
38         return;
39     }
40     if(r<=itree[num].mid)
41         Insert(l,r,h,num<<1);
42     else if(l>=itree[num].mid)
43         Insert(l,r,h,(num<<1)+1);
44     else
45     {    Insert(l,itree[num].mid,h,num<<1);
46         Insert(itree[num].mid,r,h,(num<<1)+1);
47     }
48 }
49
50
51 int hash[MaxSize];
52
53 long long Calc(int h,int num)
54 {    if(h>itree[num].hight)
55         itree[num].hight=h;
56     if(itree[num].left+1==itree[num].right)
57     {    return (long long)itree[num].hight*(hash[itree[num].right]-hash[itree[num].left]);
58     }
59     return Calc(itree[num].hight,num<<1)+Calc(itree[num].hight,(num<<1)+1);
60 }
61
62 int BinarySearch(int *from,int *end,int key)
63 {    int low=0,high=end-from;
64     int mid=(low+high)/2;
65     while(low<=high)
66         if(from[mid]==key)
67             return mid;
68         else if(from[mid]>key)
69         {    high=mid-1;
70             mid=(high+low)/2;
71         }
72         else
73         {    low=mid+1;
74             mid=(high+low)/2;
75         }
76     return mid;
77 }
78
79
80 int main()
81 {
82     int N;
83     scanf("%d",&N);
84     for(int i=0;i<N;i++)
85     {    scanf("%d%d%d",&b[i].left,&b[i].right,&b[i].hight);
86         hash[i<<1]=b[i].left;
87         hash[(i<<1)+1]=b[i].right;
88     }
89     int hlen=0;
90     sort(hash,hash+2*N);
91     sort(b,b+N,cmp);
92     for(int i=0;i<2*N-1;i++)
93         if(hash[i]!=hash[i+1])
94             hash[++hlen]=hash[i+1];
95     hlen++;
96     Build(0,hlen,1);
97     for(int i=0;i<N;i++)
98     {    int l=BinarySearch(hash,hash+hlen,b[i].left);
99         int r=BinarySearch(hash,hash+hlen,b[i].right);
100         Insert(l,r,b[i].hight,1);
101     }
102     cout<<Calc(0,1)<<endl;
103     //printf("%I64d\n",Calc(0,1));
104     return 0;
105 }

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POJ 3277 City Horizon