HDU-2795 Billboard

Billboard

Time Limit: 20000/8000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)


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
  ————————————————————集训23.1的分割线————————————————————
前言:好羞耻…………QAQ又开始抄袭胡大大的线段树了!
思路:可贴海报的行编号为1~h,则以1~h为区间,划分出一棵线段树,叶结点保存剩余可贴的长度,其余则保存该区间内所有行允许的最大长度。因为询问就是更新,所以不必update了,直接询问的时候push_up即可。
胡大大代码如下:
/*
ID: j.sure.1
PROG:
LANG: C++
*/
/****************************************/
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <stack>
#include <queue>
#include <vector>
#include <map>
#include <string>
#include <iostream>
#define INF 0x3f3f3f3f
#define LL long long
using namespace std;
/****************************************/
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
const int maxn = 2e5+5;
int h, w, n;
int tree[maxn<<2];
//优先向上,则把h作为线段树区间,每次优先向左,就是优先放在h值小的位置
///结点中保存行号为h的行能够容纳的w,区间中保存这几行能够容纳的最大w,这样就可以查找到这个可以放海报的位置
void build(int l, int r, int rt)
{
	tree[rt] = w;
	if(l == r) return ;
	int m = (l+r) >> 1;
	build(lson); build(rson);
}

void push_up(int rt)
{
	tree[rt] = max(tree[rt<<1], tree[rt<<1|1]);
}

int query(int cur, int l, int r, int rt)
{
	if(l == r) {
		tree[rt] -= cur;//找到了确定的位置,贴上海报,更新
		return l;
	}
	int m = (l + r) >> 1;
	int ret;
	if(cur <= tree[rt<<1])
		ret = query(cur, lson);
	else
		ret = query(cur, rson);
	push_up(rt);//查询结束的时候 单点被更新,向上推
	return ret;
}

int main()
{
#ifdef J_Sure
//	freopen("000.in", "r", stdin);
//	freopen(".out", "w", stdout);
#endif
	while(~scanf("%d%d%d", &h, &w, &n)) {
		if(h > n) h = n;//小剪枝
		build(1, h, 1);
		while(n--) {
			int cur;
			scanf("%d", &cur);
			if(tree[1] < cur) puts("-1");
			else printf("%d\n", query(cur, 1, h, 1));
		}
	}
	return 0;
}



### 关于HDU - 6609 的题目解析 由于当前未提供具体关于 HDU - 6609 题目的详细描述,以下是基于一般算法竞赛题型可能涉及的内容进行推测和解答。 #### 可能的题目背景 假设该题目属于动态规划类问题(类似于多重背包问题),其核心在于优化资源分配或路径选择。此类问题通常会给出一组物品及其属性(如重量、价值等)以及约束条件(如容量限制)。目标是最优地选取某些物品使得满足特定的目标函数[^2]。 #### 动态转移方程设计 如果此题确实是一个变种的背包问题,则可以采用如下状态定义方法: 设 `dp[i][j]` 表示前 i 种物品,在某种条件下达到 j 值时的最大收益或者最小代价。对于每一种新加入考虑范围内的物体 k ,更新规则可能是这样的形式: ```python for i in range(n): for s in range(V, w[k]-1, -1): dp[s] = max(dp[s], dp[s-w[k]] + v[k]) ``` 这里需要注意边界情况处理以及初始化设置合理值来保证计算准确性。 另外还有一种可能性就是它涉及到组合数学方面知识或者是图论最短路等相关知识点。如果是后者的话那么就需要构建相应的邻接表表示图形结构并通过Dijkstra/Bellman-Ford/Floyd-Warshall等经典算法求解两点间距离等问题了[^4]。 最后按照输出格式要求打印结果字符串"Case #X: Y"[^3]。 #### 示例代码片段 下面展示了一个简单的伪代码框架用于解决上述提到类型的DP问题: ```python def solve(): t=int(input()) res=[] cas=1 while(t>0): n,k=list(map(int,input().split())) # Initialize your data structures here ans=find_min_unhappiness() # Implement function find_min_unhappiness() res.append(f'Case #{cas}: {round(ans)}') cas+=1 t-=1 print("\n".join(res)) solve() ```
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