hdu 2795 Billboard(线段树 求最值的位置)

Billboard

Time Limit: 20000/8000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3119    Accepted Submission(s): 1506

Problem Description

At the entrance to the university, there is a huge rectangular billboard of size h*w (h is its height and w is its width). The board is the place where all possible announcements are posted: nearest programming competitions, changes in the dining room menu, and other important information.

On September 1, the billboard was empty. One by one, the announcements started being put on the billboard.

Each announcement is a stripe of paper of unit height. More specifically, the i-th announcement is a rectangle of size 1 * wi.

When someone puts a new announcement on the billboard, she would always choose the topmost possible position for the announcement. Among all possible topmost positions she would always choose the leftmost one.

If there is no valid location for a new announcement, it is not put on the billboard (that's why some programming contests have no participants from this university).

Given the sizes of the billboard and the announcements, your task is to find the numbers of rows in which the announcements are placed.

 

Input

There are multiple cases (no more than 40 cases).

The first line of the input file contains three integer numbers, h, w, and n (1 <= h,w <= 10^9; 1 <= n <= 200,000) - the dimensions of the billboard and the number of announcements.

Each of the next n lines contains an integer number wi (1 <= wi <= 10^9) - the width of i-th announcement.

 

Output

For each announcement (in the order they are given in the input file) output one number - the number of the row in which this announcement is placed. Rows are numbered from 1 to h, starting with the top row. If an announcement can't be put on the billboard, output "-1" for this announcement.

 

Sample Input

   
   
   
   

    
    
    
    3 5 5
2
4
3
3
3
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    1
2
1
3
-1
   
   
   
   

 

Author

hhanger@zju

 

Source

HDOJ 2009 Summer Exercise（5）

 

Recommend

lcy

 

题目：http://acm.hdu.edu.cn/showproblem.php?pid=2795

题意：这题给出一个h*w的板子，在板子上贴n个1*wi的广告，要求每个广告尽量考上方，在此前提下尽量靠左边，要求输出每个广告在第几行

分析：其实最多就只能用到n行，所以h取h和n的最小值即可，将其转化为h个元素的线段树，表示第i行现在剩下的宽度，线段树维护区间的最大值，每次都查找大于wi的最小行标号就行。。。

代码：

#include<cstdio>
#include<cstring>
#include<iostream>
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
using namespace std;
const int mm=888888;
int val[mm];
int i,n,h,w;
void pushup(int rt)
{
    val[rt]=max(val[rt<<1],val[rt<<1|1]);
}
void build(int l,int r,int rt)
{
    val[rt]=w;
    if(l==r)return;
    int m=(l+r)>>1;
    build(lson);
    build(rson);
}
int updata(int v,int l,int r,int rt)
{
    if(l==r)
    {
        val[rt]-=v;
        return l;
    }
    int m=(l+r)>>1,ret=(val[rt<<1]>=v)?updata(v,lson):updata(v,rson);
    if(ret>-1)pushup(rt);
    return ret;
}
int main()
{
    while(~scanf("%d%d%d",&h,&w,&n))
    {
        h=min(n,h);
        build(1,h,1);
        while(n--)
        {
            scanf("%d",&i);
            printf("%d\n",val[1]<i?-1:updata(i,1,h,1));
        }
    }
    return 0;
}