【POJ 2482】 Stars in Your Windows

【题目链接】

http://poj.org/problem?id=2482

【算法】

线段树 + 扫描线

【代码】

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cerrno>
#include <clocale>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <limits>
#include <list>
#include <map>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <utility>
#include <vector>
#include <cwchar>
#include <cwctype>
#include <stack>
#include <limits.h>
using namespace std;
#define MAXN 10010
typedef long long ll;

struct info
{
        ll x,l,r,v;
} a[MAXN<<];

ll i,n,w,h,len,lth,ans,l,r;
ll x[MAXN],y[MAXN],c[MAXN],val[MAXN<<];

struct SegmentTree
{
        struct Node
        {
                ll l,r;
                ll mx,tag;
        } Tree[MAXN<<];
        inline void build(ll index,ll l,ll r)
        {
                ll mid;
                Tree[index].l = l; Tree[index].r = r;
                Tree[index].mx = ;
                if (l == r) return;
                mid = (Tree[index].l + Tree[index].r) >> ;
                build(index<<,l,mid);
                build(index<<|,mid+,r);
        }
        inline void update(ll index)
        {
                Tree[index].mx = max(Tree[index<<].mx,Tree[index<<|].mx);
        }
        inline void pushdown(ll index)
        {
                 if (Tree[index].tag)
                 {
                         Tree[index<<].mx += Tree[index].tag;
                        Tree[index<<|].mx += Tree[index].tag;
                        Tree[index<<].tag += Tree[index].tag;
                        Tree[index<<|].tag += Tree[index].tag;
                        Tree[index].tag = ;
                }
        }
        inline void add(ll index,ll l,ll r,ll val)
        {
                ll mid;
                if (l > r) return;
                if (Tree[index].l == l && Tree[index].r == r)
                {
                        Tree[index].mx += val;
                        Tree[index].tag += val;
                } else
                {
                        pushdown(index);
                        mid = (Tree[index].l + Tree[index].r) >> ;
                        if (mid >= r) add(index<<,l,r,val);
                        else if (mid +  <= l) add(index<<|,l,r,val);
                        else
                        {
                                add(index<<,l,mid,val);
                                add(index<<|,mid+,r,val);
                        }
                        update(index);
                }
        }
        inline ll get()
        {
                return Tree[].mx;
        }
} T;
inline bool cmp(info a,info b)
{
        return (a.x != b.x) ? (a.x < b.x) : (a.v < b.v);
}

int main()
{

        while (scanf("%lld%lld%lld",&n,&w,&h) != EOF)
        {
                    len = lth = ans = ;
                    for (i = ; i <= n; i++)
                    {
                            scanf("%lld%lld%lld",&x[i],&y[i],&c[i]);
                            a[++len] =     (info){x[i],y[i],y[i]+h,c[i]};
                            a[++len] =  (info){x[i]+w,y[i],y[i]+h,-c[i]};
                            val[++lth] = y[i];
                            val[++lth] = y[i] + h;
                    }
                    sort(val+,val+lth+);
                    lth = unique(val+,val+lth+) - val - ;
                    sort(a+,a+len+,cmp);
                    T.build(,,lth);
                    for (i = ; i <= len; i++)
                    {
                            l = lower_bound(val+,val+lth+,a[i].l) - val;
                            r = lower_bound(val+,val+lth+,a[i].r) - val - ;
                            T.add(,l,r,a[i].v);
                            ans = max(ans,T.get());
                    }
                    printf("%lld\n",ans);
        } 

        return ;      

}