xtu数据结构 H. City Horizon

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <vector>
 6 #include <climits>
 7 #include <algorithm>
 8 #include <cmath>
 9 #define LL long long
10 #define INF 0x3f3f3f
11 using namespace std;
12 const int maxn = 40010;
13 struct Building{
14     LL a,b,h;
15 }bb[maxn];
16 struct node{
17     int lt,rt,h;
18 }tree[maxn<<3];
19 LL p[maxn<<1],n,ans;
20 int cnt;
21 bool cmp(const Building &x,const Building &y){
22     return x.h < y.h;
23 }
24 void build(int lt,int rt,int v){
25     tree[v].lt = lt;
26     tree[v].rt = rt;
27     tree[v].h = 0;
28     if(rt-lt == 1) return;
29     int mid = (lt+rt)>>1;
30     build(lt,mid,v<<1);
31     build(mid,rt,v<<1|1);
32 }
33 void update(int lt,int rt,int val,int v){
34     if(tree[v].lt == lt && tree[v].rt == rt){
35         tree[v].h = val;
36         return;
37     }
38     if(tree[v].h > 0){
39         tree[v<<1].h = tree[v<<1|1].h = tree[v].h;
40         tree[v].h = 0;
41     }
42     int mid = (tree[v].lt+tree[v].rt)>>1;
43     if(rt <= mid) update(lt,rt,val,v<<1);
44     else if(lt >= mid) update(lt,rt,val,v<<1|1);
45     else{
46         update(lt,mid,val,v<<1);
47         update(mid,rt,val,v<<1|1);
48     }
49 }
50 void query(int v){
51     if(tree[v].h > 0){
52         ans += (LL)tree[v].h*(p[tree[v].rt-1] - p[tree[v].lt-1]);
53         return;
54     }
55     if(tree[v].rt - tree[v].lt == 1) return;
56     query(v<<1);
57     query(v<<1|1);
58 }
59 int bsearch(int lt,int rt,int val){
60     while(lt <= rt){
61         int mid = (lt+rt)>>1;
62         if(p[mid] == val)
63             return mid+1;
64         else if(val < p[mid])
65          rt = mid-1;
66         else lt = mid+1;
67     }
68     return 0;
69 }
70 int main(){
71     int i,j,r;
72     scanf("%lld",&n);
73     for(i = 0; i < n; i++){
74         scanf("%d%d%d",&bb[i].a,&bb[i].b,&bb[i].h);
75         p[cnt++] = bb[i].a;
76         p[cnt++] = bb[i].b;
77     }
78     sort(p,p+cnt);//排序是为了使用二分查找。
79     sort(bb,bb+n,cmp);
80     build(1,n<<1,1);
81     r = (n<<1)-1;
82     for(i = 0; i < n; i++){
83         int lt = bsearch(0,cnt-1,bb[i].a);
84         int rt = bsearch(0,cnt-1,bb[i].b);
85         update(lt,rt,bb[i].h,1);
86     }
87     ans = 0;
88     query(1);
89     printf("%lld",ans);
90     return 0;
91 }