HDU 1312：Red and Black

Red and Black

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 17510    Accepted Submission(s): 10642

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

一個簡單的深搜題目，給出地圖，‘.’是可以走的區域，起點是‘@’，問在這個起點開始走可以遇到多少個‘.’;

AC代碼：

#include<cstdio>
#include<cstring>
#include<iostream>
#include<math.h>
#include<algorithm>
using namespace std;
char mapp[25][25];
bool visit[25][25];
int s,w,h;;
void DFS(int x,int y)
{
    if(x>=0&&x<h&&y>=0&&y<w&&mapp[x][y]!='#'&&!visit[x][y]) //如果在地圖内并且該電是‘.’并且沒有周遊過
    {
        s++;
        visit[x][y]=true;                //标記已周遊
        DFS(x+1,y);                      //四個方向
        DFS(x,y+1);
        DFS(x,y-1);
        DFS(x-1,y);
    }
}
int main()
{
    while(cin>>w>>h&&(w||h))
    {
        int x,y;
        s=0;
        memset(visit,0,sizeof(visit));  //初始化visit數組
        for(int i=0; i<h; i++)
        {
            cin>>mapp[i];
            for(int j=0; j<w; j++)      //對每一行查找起點
                if(mapp[i][j]=='@')x=i,y=j;
        }
        DFS(x,y);                       //深度優先周遊
        cout<<s<<endl;
    }
    return 0;
}