poj2482

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<cmath>
#define L(x) (x<<1)
#define R(x) (x<<1|1)
#define MAX 30010
using namespace std;
class line
{
public:
    long long x,y1,y2;
    int flag;
    line(){}
    line(long long a ,long long b, long long c, int d):x(a),y1(b),y2(c),flag(d)
    {}
    bool operator <(const line b)const
    {
        if(x!=b.x)
          return x<b.x;
        return flag>b.flag;
    }
}lines[MAX*2];
long long cy[MAX*2];
struct node
{
    int l,r,cover,max;
}a[MAX*3];
void build(int t ,int l, int r)
{
    a[t].l=l;
    a[t].r=r;
    a[t].cover=0;
    a[t].max=0;
    if(l==r)return;
    int mid=(l+r)>>1;
    build(L(t),l,mid);
    build(R(t),mid+1,r);
}
void update(int t,line s)
{
    if(s.y1<=cy[a[t].l]&&cy[a[t].r]<=s.y2)
    {
        a[t].cover+=s.flag;
        a[t].max+=s.flag;
        return;
    }
    if(a[t].l==a[t].r)return;
    a[L(t)].cover+=a[t].cover;
    a[L(t)].max+=a[t].cover;
    a[R(t)].cover+=a[t].cover;
    a[R(t)].max+=a[t].cover;
    a[t].cover=0;
    int mid=(a[t].l+a[t].r)>>1;
    if(s.y1<=cy[mid])
      update(L(t),s);
    if(s.y2>cy[mid])
      update(R(t),s);
    a[t].max=max(a[L(t)].max,a[R(t)].max);
}
int main()
{
    int m,i,val;
    long long w,h,x,y;
    int numl,numy;
    int ans;
    while(scanf("%d%lld%lld",&m,&w,&h)!=EOF)
    {
    	if(w==0||h==0)
    	{
    		printf("0\n");
    		continue;
    	}
        numl=0;
        numy=0;
        ans=0;
        while(m--)
        {
            scanf("%lld%lld%d",&x,&y,&val);
            lines[numl++]=line(x,y,y+h-1,val);
            lines[numl++]=line(x+w-1,y,y+h-1,-val);
            cy[numy++]=y;
            cy[numy++]=y+h-1;
        }
        sort(cy,cy+numy);
        sort(lines,lines+numl);
        numy=unique(cy,cy+numy)-cy;
        build(1,0,numy-1);
        for(i=0;i<numl;i++)
        {
            update(1,lines[i]);
            ans=max(ans,a[1].max);
        }
        printf("%d\n",ans);
    }
}