HDU 5091 Beam Cannon

Source: Internet
Author: User

Main topic:

There are n points (n<=10000), the coordinates of the point are not more than 20000, and then ask you to use a w*h (1<=w,h<=40000) Rectangle, the edge of the rectangle parallel to the axis, the maximum number of points can be covered.

Rujia Black Book has the original problem

The code below is discretized, scanned with a straight line perpendicular to the x axis, and a line tree on the y axis, so for each point (x, y), give the weight of 1, and then add a new negative point (x+w,y), giving the weight-1. When the scan line sweeps through each point, the segment tree is updated with the weighted value of the point. Maintain the sum value for each interval, because it is an interval update, so you have to make a lazy tag.

1#include <stdio.h>2#include <stdlib.h>3#include <math.h>4#include <string.h>5#include <iostream>6#include <string>7#include <map>8#include <Set>9#include <algorithm>Ten#include <queue> One#include <vector> A #defineN 40000 - using namespacestd; -  the structNode - { -     intL,r,lazy; -     intsum; +} node[n<<2]; - struct Line + { A     intx,y1,y2,v; at Line () {} -Line (intAintBintCintd) -     { -x=a,y1=b,y2=c,v=D; -     } -     BOOL operator< (ConstLine&a)Const in     { -         if(x==a.x) to             returnV>A.V; +         returnx<a.x; -     } the } Line[n]; * intLisan[n]; $ intCnt=0;Panax Notoginseng voidPushup (intRT) - { theNode[rt].sum=max (node[rt<<1].sum,node[rt<<1|1].sum); + } A voidPushdown (intRT) the { +     if(Node[rt].lazy) -     { $node[rt<<1].lazy+=Node[rt].lazy; $node[rt<<1|1].lazy+=Node[rt].lazy; -node[rt<<1].sum+=Node[rt].lazy; -node[rt<<1|1].sum+=Node[rt].lazy; thenode[rt].lazy=0; -     }Wuyi } the voidBuildintRtintLintR) - { Wunode[rt].sum=0, node[rt].lazy=0; -Node[rt].l=l,node[rt].r=R; About     if(l==R) $         return; -     intMid=l+r>>1; -Build (rt<<1, l,mid); -Build (rt<<1|1, mid+1, R); A pushup (RT); + } the voidUpdateintRtintLintRintv) - { $     if(l<=node[rt].l&&node[rt].r<=R) the     { thenode[rt].lazy+=v; thenode[rt].sum+=v; the         return; -     } in pushdown (RT); the     intMid=node[rt].l+node[rt].r>>1; the     if(l<=mid) AboutUpdate (rt<<1, l,r,v); the     if(r>mid) theUpdate (rt<<1|1, l,r,v); the pushup (RT); + } - intQueryintRtintLintR) the {Bayi     if(l<=node[rt].l&&node[rt].r<=R) the     { the         returnnode[rt].sum; -     } - pushdown (RT); the     intMid=node[rt].l+node[rt].r>>1, ans=0; the     if(l<=mid) theAns+=query (rt<<1, l,r); the     if(r>mid) -Ans+=query (rt<<1|1, l,r); the     returnans; the } the intMain ()94 { the     intn,w,h; the      while(SCANF ("%d",&N)) the     {98Cnt=0; About         if(n<0) -              Break;101scanf"%d%d",&w,&h);102          for(intI=0; i<n;++i)103         {104             intx, y; thescanf"%d%d",&x,&y);106x+=20001;107y+=20001;108lisan[cnt]=y;109Line[cnt++]=line (X,y,y+h,1); thelisan[cnt]=y+h;111Line[cnt++]=line (x+w,y,y+h,-1); the         }113Sort (line,line+CNT); theSort (lisan,lisan+CNT); the         intNum=unique (LISAN,LISAN+CNT)-Lisan; theBuild1,0, num-1);117         intans=0;118          for(intI=0; i<cnt;++i)119         { -             intL=lower_bound (LISAN,LISAN+NUM,LINE[I].Y1)-Lisan;121             intR=lower_bound (Lisan,lisan+num,line[i].y2)-Lisan;122Update1, L,R,LINE[I].V);123Ans=max (ans,node[1].sum);124         } theprintf"%d\n", ans);126     }127  -}

HDU 5091 Beam Cannon

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.