HDU 3016 线段树+简单dp

        题目连接：http://acm.hdu.edu.cn/showproblem.php?pid=3016

        

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
struct Board
{
    int h;
    int l;
    int r;
    int v;
};
struct Line
{
    int l;
    int r;
};
struct node
{
    int s;
    int e;
    int f;
};
Board a[2000000];
node tr[1000000];
Line l[4000000];
int dp[2000000];
bool cmp(Board a,Board b)
{
    return a.h<b.h;
}
void build_tree(int c,int s,int e)
{
    tr[c].s=s;
    tr[c].e=e;
    tr[c].f=0;
    if (s == e)
        return ;
    build_tree(c<<1,s,(s+e)>>1);
    build_tree(c<<1|1,((s+e)>>1)+1,e);
}
void update(int c,int s,int e,int f)
{
    if (tr[c].s > e || s > tr[c].e)
        return ;
    if (tr[c].s >= s && tr[c].e <= e)
    {
        tr[c].f=f;
        return ;
    }
    if (tr[c].f != -1)
    {
        tr[c<<1].f=tr[c].f;
        tr[c<<1|1].f=tr[c].f;
        tr[c].f=-1;
    }
    update(c<<1,s,e,f);
    update(c<<1|1,s,e,f);
}
int query(int c,int v)
{
    if (tr[c].f != -1 && tr[c].s <= v && tr[c].e >= v)
        return tr[c].f;
    if (v > (tr[c].s+tr[c].e)>>1)
        return query(c<<1|1,v);
    else
        return query(c<<1,v);
}
int main()
{
    int n,lt,i,ma;
    while (scanf("%d",&n) != EOF)
    {
        ma=0;
        for (i=1;i<=n; i++)
        {
            scanf("%d%d%d%d",&a[i].h,&a[i].l,&a[i].r,&a[i].v);
            if(a[i].l>ma)
                ma=a[i].l;
            if(a[i].r>ma)
                ma=a[i].r;
        }
        lt=0;
        sort(a+1,a+n+1,cmp);
        build_tree(1,1,ma);
        for (i=1; i<=n; i++)
        {
            l[i].l=query(1,a[i].l);
            l[i].r=query(1,a[i].r);
            update(1,a[i].l,a[i].r,i);
        }
        memset(dp,0,sizeof(dp));
        dp[n]=100+a[n].v;
        for (i=n; i>=1; i--)
        {
            if (dp[i] != 0)
            {
                dp[l[i].l]=dp[l[i].l]>dp[i]+a[l[i].l].v?dp[l[i].l]:dp[i]+a[l[i].l].v;
                dp[l[i].r]=dp[l[i].r]>dp[i]+a[l[i].r].v?dp[l[i].r]:dp[i]+a[l[i].r].v;
            }
        }
        if (dp[0] <= 0)
            printf("-1\n");
        else
            printf("%d\n",dp[0]);
    }
}