HDU 1045 Fire Net
来源:互联网 发布:图片识别手写数字算法 编辑:程序博客网 时间:2024/06/04 00:22
Fire Net
题目链接
Time Limit : 2000/1000ms (Java/Other) Memory Limit : 65536/32768K (Java/Other)
Total Submission(s) : 8 Accepted Submission(s) : 7
Problem Description
Suppose that we have a square city with straight streets. A map of a city is a square board with n rows and n columns, each representing a street or a piece of wall.
A blockhouse is a small castle that has four openings through which to shoot. The four openings are facing North, East, South, and West, respectively. There will be one machine gun shooting through each opening.
Here we assume that a bullet is so powerful that it can run across any distance and destroy a blockhouse on its way. On the other hand, a wall is so strongly built that can stop the bullets.
The goal is to place as many blockhouses in a city as possible so that no two can destroy each other. A configuration of blockhouses is legal provided that no two blockhouses are on the same horizontal row or vertical column in a map unless there is at least one wall separating them. In this problem we will consider small square cities (at most 4x4) that contain walls through which bullets cannot run through.
The following image shows five pictures of the same board. The first picture is the empty board, the second and third pictures show legal configurations, and the fourth and fifth pictures show illegal configurations. For this board, the maximum number of blockhouses in a legal configuration is 5; the second picture shows one way to do it, but there are several other ways.
Your task is to write a program that, given a description of a map, calculates the maximum number of blockhouses that can be placed in the city in a legal configuration.
Input
The input file contains one or more map descriptions, followed by a line containing the number 0 that signals the end of the file. Each map description begins with a line containing a positive integer n that is the size of the city; n will be at most 4. The next n lines each describe one row of the map, with a ‘.’ indicating an open space and an uppercase ‘X’ indicating a wall. There are no spaces in the input file.
Output
For each test case, output one line containing the maximum number of blockhouses that can be placed in the city in a legal configuration.
Sample Input4.X......XX......2XX.X3.X.X.X.X.3....XX.XX4................0Sample Output51524SourceZhejiang University Local Contest 2001
皇后问题的变形,可以直接无脑递归的
#include<algorithm>#include<iostream>#include<cstring>#include<cstdio>using namespace std;int n,m,t,num;char a[1000][1000];int state[1000][1000];int sta(int x,int y)//判断上下左右四个方向的有没有标记,特殊情况有X时间后面被标记也无所谓的{ for(int i=0;i<x;i++) { if(a[i][y]=='X') break; if(state[i][y]==1) { return 1; } } for(int i=x+1;i<t;i++) { if(a[i][y]=='X') break; if(state[i][y]==1) { return 1; } } for(int j=0;j<y;j++) { if(a[x][j]=='X') break; if(state[x][j]==1) return 1; } for(int j=y+1;j<t;j++) { if(a[x][j]=='X') break; if(state[x][j]==1) return 1; } return 0;}void dfs(int k)//无脑递归把每种情况都试一遍{ if(k>num) num=k; for(int i=0;i<t;i++) { for(int j=0;j<t;j++) { if(a[i][j]!='X'&&state[i][j]!=1) { if(sta(i,j)==0) { state[i][j]=1; dfs(k+1); state[i][j]=0; } } } }}int main(){ while(scanf("%d",&t)&&t!=0) { for(int i=0;i<t;i++) { scanf("%s",a[i]); } num=0; memset(state,0,sizeof(state)); dfs(0); printf("%d\n",num); } return 0;}
- hdu 1045 Fire Net
- HDU 1045 Fire Net
- HDU 1045 Fire Net
- Hdu 1045 Fire Net
- HDU 1045 Fire Net
- hdu 1045 Fire Net
- HDU-1045-Fire Net
- hdu 1045 Fire Net
- hdu 1045 Fire Net
- HDU 1045 Fire Net
- hdu 1045 Fire Net
- HDU-1045 Fire Net
- HDU:1045 Fire Net
- HDU 1045 Fire Net
- HDU 1045 Fire Net
- hdu 1045 Fire Net
- hdu 1045 Fire Net
- hdu 1045 Fire Net
- 解决VS2005 VS2008 vs2010断点无效-源代码与原始版本不同
- 欢迎使用CSDN-markdown编辑器
- Web前端性能优化策略
- mac上mysql中文乱码问题
- 职称论文发表途径
- HDU 1045 Fire Net
- Caused by: java.net.SocketException: Software caused connection abort: socket write error
- Java知识:HashSet详解
- css居中,进度条
- css的各种居中
- 数据结构之双向链表
- STM32F429HAL库ADCDMA学习笔记
- Mac 下MAMP Pro MySQL无法启动报 Error: could not open single-table tablespace file ./mysql/innodb_table_sta
- 详解内部类