1645: [usaco open] city horizon

Source: Internet
Author: User
1645: [usaco open] city horizon time limit: 5 sec memory limit: 64 MB
Submit: 315 solved: 157
[Submit] [Status] Description

Farmer John has taken his cows on a trip to the city! As the sun sets, the cows gaze at the city horizon and observe the beautiful silhouettes formed by the rectangular buildings. the entire horizon is represented by a number line with N (1 <= n <= 40,000) buildings. building I's silhouette has a base that spans locations a_ I through B _ I along the horizon (1 <= a_ I <B _ I <= 1,000,000,000) and has height h_ I (1 <=h_ I <= 1,000,000,000 ). determine the area, in square units, of the aggregate silhouette formed by all N buildings.

N rectangle blocks, intersection area and.


* Line 1: A single INTEGER: N

* Lines 2. n + 1: input line I + 1 describes building I with three space-separated integers: a_ I, B _ I, and h_ I


* Line 1: The total area, in square units, of the silhouettes formed by all N buildings

Sample input4
2 5 1
9 10 4
6 8 2
4 6 3
Sample output16

Output details:

The first building overlaps with the fourth building for an area of 1
Square unit, so the total area is just 3*1 + 1*4 + 2*2 + 2*3-1 = 16. hintsource


Question: the idea of this question is clever.
All the images are divided into 2 * n-1 rectangles. Therefore, you only need to maintain the height of each rectangle using the line segment tree.
Code: (copy)
 1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<cmath> 5 #include<algorithm> 6 #define ll long long 7 #define inf 10000000000 8 using namespace std; 9 inline ll read()10 {11     int x=0,f=1;char ch=getchar();12     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}13     while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}14     return x*f;15 }16 int n;17 int x[40005],y[40005],val[40005],disc[80005];18 struct seg{int l,r,mx,tag;}t[320005];19 int find(int x)20 {21     int l=1,r=2*n;22     while(l<=r)23     {24         int mid=(l+r)>>1;25         if(disc[mid]<x)l=mid+1;26         else if(disc[mid]==x)return mid;27         else r=mid-1;28     }29 }30 void pushdown(int k)31 {32     if(t[k].l==t[k].r)return;33     int tag=t[k].tag;t[k].tag=0;34     if(tag)35     {36         t[k<<1].tag=max(t[k<<1].tag,tag);37         t[k<<1|1].tag=max(t[k<<1|1].tag,tag);38         t[k<<1].mx=max(t[k<<1].mx,tag);39         t[k<<1|1].mx=max(t[k<<1|1].mx,tag);40     }41 }42 void build(int k,int l,int r)43 {44     t[k].l=l;t[k].r=r;45     if(l==r)return;46     int mid=(l+r)>>1;47     build(k<<1,l,mid);build(k<<1|1,mid+1,r);48 }49 void update(int k,int x,int y,int val)50 {51     pushdown(k);52     int l=t[k].l,r=t[k].r;53     if(l==x&&y==r)54     {55         t[k].tag=val;t[k].mx=max(t[k].mx,val);56         return;57     }58     int mid=(l+r)>>1;59     if(y<=mid)update(k<<1,x,y,val);60     else if(x>mid)update(k<<1|1,x,y,val);61     else62     {63         update(k<<1,x,mid,val);update(k<<1|1,mid+1,y,val);64     }65 }66 int query(int k,int x)67 {68     pushdown(k);69     int l=t[k].l,r=t[k].r;70     if(l==r)return t[k].mx;71     int mid=(l+r)>>1;72     if(x<=mid)return query(k<<1,x);73     else return query(k<<1|1,x);74 }75 int main()76 {77     n=read();build(1,1,n<<1);78     for(int i=1;i<=n;i++)79     {80         x[i]=read(),y[i]=read(),val[i]=read();81         disc[(i<<1)-1]=x[i];disc[i<<1]=y[i];82     }83     sort(disc+1,disc+(n<<1)+1);84     for(int i=1;i<=n;i++)85         x[i]=find(x[i]),y[i]=find(y[i]);86     for(int i=1;i<=n;i++)87     {88         update(1,x[i],y[i]-1,val[i]);89     }90     ll ans=0;91     for(int i=1;i<2*n;i++)92     {93         ans+=(ll)query(1,i)*(disc[i+1]-disc[i]);94     }95     printf("%lld",ans);96     return 0;97 }
View code


1645: [usaco open] city horizon

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.