hdu1312 Red and Black(DFS深搜，入门题目)

1）注意刚开始是输入列数n，行数m

#include <iostream>
#include <string.h>
using namespace std;
const int maxx=23;
int dir[4][2]={-1,0,1,0,0,1,0,-1};//上下左右
int step;
int m,n;
char room[maxx][maxx];
bool bj[maxx][maxx];
void DFS(int x,int y)
{
    bj[x][y]=true;
    for(int i=0;i<4;i++){
        int a=x+dir[i][0];
        int b=y+dir[i][1];
        if(0<=a&&0<=b&&a<m&&b<n&&!bj[a][b]&&room[a][b]=='.'){
            //bj[a][b]==true;
            step++;
            DFS(a,b);
        }
    }
    //return step;
}
int main()
{
    int x;
    int y;
    while(cin>>n>>m&&(m||n)){
        memset(bj,0,sizeof(bj));
        //bj[maxx][maxx]=false;
        step=1;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                cin>>room[i][j];
                if(room[i][j]=='@'){
                   x=i;
                   y=j;
                }
            }
        }
        DFS(x,y);
        cout<<step<<endl;
    }
    return 0;
}

2)

Red and Black

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 15063    Accepted Submission(s): 9325

Problem Description

There is a rectangular room, covered with square tiles. Each tile is colored either red or black. A man is standing on a black tile. From a tile, he can move to one of four adjacent tiles. But he can't move on red tiles, he can move only on black tiles.

Write a program to count the number of black tiles which he can reach by repeating the moves described above. 

 

Input

The input consists of multiple data sets. A data set starts with a line containing two positive integers W and H; W and H are the numbers of tiles in the x- and y- directions, respectively. W and H are not more than 20.

There are H more lines in the data set, each of which includes W characters. Each character represents the color of a tile as follows.

'.' - a black tile 
'#' - a red tile 
'@' - a man on a black tile(appears exactly once in a data set) 

 

Output

For each data set, your program should output a line which contains the number of tiles he can reach from the initial tile (including itself). 

 

Sample Input

   
   
   
   

    
    
    
    6 9
....#.
.....#
......
......
......
......
......
#@...#
.#..#.
11 9
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
0 0
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    45
59
6
13