HDU 2795 Billboard(线段树,单点更新)

# include<cstdio>
# include<iostream>

using namespace std;

int h,w,n;
# define MAX 200004
# define lid id<<1
# define rid id<<1|1

struct Segtree
{
    int l,r;
    int mx;
}tree[MAX*4];

void push_up ( int id )
{
    tree[id].mx=max(tree[lid].mx,tree[rid].mx);
}

void build( int id,int l,int r )
{
    tree[id].l = l; tree[id].r = r;
    tree[id].mx = w;
    if ( l==r )
    {
        return;
    }
    int mid = ( tree[id].l+tree[id].r )/2;
    build(lid,l,mid);
    build(rid,mid+1,r);
    push_up(id);
}

int query( int id,int val )
{
    if ( tree[id].l==tree[id].r )
    {
        tree[id].mx-=val;
        return tree[id].l;
    }
    int pos = 0;
    if ( tree[lid].mx >= val )
        pos = query(lid,val);
    else
        pos = query(rid,val);
    push_up(id);
    return pos;
}

int main(void)
{
    while ( scanf("%d%d%d",&h,&w,&n)!=EOF )
    {
        if ( h > MAX )
            h = MAX;
        build(1,1,h);
        for ( int i = 0;i < n;i++ )
        {
            int tmp; scanf("%d",&tmp);
            if ( tree[1].mx < tmp )
                printf("-1\n");
            else
            {
                int ans = query(1,tmp);
                printf("%d\n",ans);
            }
        }
    }

    return 0;
}