@(HDU)[Stirling數, 排列組合] Problem Description There are N buildings standing in a straight line in the City, numbered from 1 to N. The heights of all the buildings are distinct and between 1 and N. You can see F buildings when you standing in front of…

[Hdu4372] Count the Buildings Description There are N buildings standing in a straight line in the City, numbered from 1 to N. The heights of all the buildings are distinct and between 1 and N. You can see F buildings when you standing in front of th…

题目链接:https://vjudge.net/problem/HDU-4372 Count the Buildings Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 2509    Accepted Submission(s): 815 Problem Description There are N buildings standin…

题面 (笔者翻译) There are N buildings standing in a straight line in the City, numbered from 1 to N. The heights of all the buildings are distinct and between 1 and N. 有n座高楼,从左往右数第 i 座楼的高度为 ai,每座高楼高度互不相同,且 1 ≤ ai ≤ n ,换言之,n座高楼高度形成的序列为1~n的一个排列. You can see…

解题关键: n的环排列的个数与n-1个元素的排列的个数相等. 首先可以肯定,无论从最左边还是从最右边看,最高的那个楼一定是可以看到的,从这里入手. 假设最高的楼的位置固定,最高楼的编号为n,那么我们为了满足条件,可以在楼n的左边分x-1组,右边分y-1组,且用每组最高的那个元素代表这一组,那么楼n的左边,从左到右,组与组之间最高的元素一定是单调递增的,且每组中的最高元素一定排在该组的最左边,每组中的其它元素可以任意排列(相当于这个组中所有元素的环排列).右边反之亦然. 最高的那个楼左边一定有x-…

Description $N$座高楼,高度均不同且为$1~N$中的数,从前向后看能看到$F$个,从后向前看能看到$B$个,问有多少种可能的排列数. $T$组询问,答案模$1000000007$.其中$n\leq 2000,T\leq 100000$ 题解: 可以考虑现将最高的拿出来,那么可以考虑左边需要有$F-1$个房子成递增关系,那么可以将左边的房子分成$F-1$个组,右边有$B-1$个房子成递减关系,也是如此. 不禁想到第一类斯特林数,$s(p,k)$是将将$p$个物体排成$k$个非空循环排…

You want to build a house on an empty land which reaches all buildings in the shortest amount of distance. You can only move up, down, left and right. You are given a 2D grid of values 0, 1 or 2, where: Each 0 marks an empty land which you can pass b…

原题链接在这里:https://leetcode.com/problems/shortest-distance-from-all-buildings/ 题目: You want to build a house on an empty land which reaches all buildings in the shortest amount of distance. You can only move up, down, left and right. You are given a 2D…

Buildings Problem's Link: http://acm.hdu.edu.cn/showproblem.php?pid=5301 Mean: n*m列的网格,删除一个格子x,y,用矩形来填充矩阵.且矩形至少有一边是在矩阵的边缘上. 要使最大矩形的面积最小,求满足条件的矩形填充方式中面积最大的矩形. analyse: 任何矩形都可以分为宽度为1的小矩形,所以只考虑矩形的可以的最小长度即可. 讨论: 不删除格子时:最小长度为min((n+1)/2,(m+1)/2) = len n =…

LTE用户文档 (如有不当的地方,欢迎指正!) 8 Mobility Model with Buildings   我们现在通过例子解释如何在 ns-3 仿真程序中使用 buildings 模型(特别是 MobilityBuildingInfo  和 BuildingPropagationModel 类) 来设置 LTE 仿真场景(包括建筑物和室内节点). 1. 包含的头文件: #include <ns3/mobility-building-info.h> #include <ns3/b…