标签:blog io ar for sp 2014 log amp as
给出N个点,和一个w*h的矩形
给出N个点的坐标,求该矩形最多可以覆盖多少个点
对每个点point(x,y)右边生成对应的点(x+w,y)值为-1;
纵向建立线段树,从左到右扫描线扫一遍,遇到点则用该点的权值更新区间(y,y+h)
#include "stdio.h" #include "string.h" #include "algorithm" using namespace std; struct Mark { int x,y,s; }mark[30010]; struct node { int l,r,x,lazy; }data[200010]; bool cmp(Mark a, Mark b) { if (a.x!=b.x) return a.x<b.x; else return a.s>b.s; } int Max(int a,int b) { if (a<b) return b; else return a; } void build(int l,int r,int k) { int mid; data[k].l=l; data[k].r=r; data[k].x=0; data[k].lazy=0; if (l==r) return ; mid=(l+r)/2; build(l,mid,k*2); build(mid+1,r,k*2+1); } void updata(int l,int r,int k,int op) { int mid; if (data[k].l==l && data[k].r==r) { data[k].x+=op; data[k].lazy+=op; return ; } if (data[k].lazy!=0) { data[k*2].x+=data[k].lazy; data[k*2].lazy+=data[k].lazy; data[k*2+1].x+=data[k].lazy; data[k*2+1].lazy+=data[k].lazy; data[k].lazy=0; } mid=(data[k].l+data[k].r)/2; if (r<=mid) updata(l,r,k*2,op); else if (l>mid) updata(l,r,k*2+1,op); else { updata(l,mid,k*2,op); updata(mid+1,r,k*2+1,op); } data[k].x=Max(data[k*2].x,data[k*2+1].x); } int main() { int n,w,h,i,x,y,ans; while (scanf("%d",&n)!=EOF) { if (n<0) break; scanf("%d%d",&w,&h); for (i=0;i<n;i++) { scanf("%d%d",&x,&y); x+=20000; y+=20000; mark[i*2].x=x; mark[i*2].y=y; mark[i*2].s=1; mark[i*2+1].x=x+w; mark[i*2+1].y=y; mark[i*2+1].s=-1; } sort(mark,mark+n*2,cmp); build(0,40000,1); ans=0; for (i=0;i<n*2;i++) { y=mark[i].y+h; if (y>40000) y=40000; updata(mark[i].y,y,1,mark[i].s); ans=Max(ans,data[1].x); } printf("%d\n",ans); } return 0; }
标签:blog io ar for sp 2014 log amp as
原文地址:http://blog.csdn.net/u011932355/article/details/40712447