hdu 1312 DFS深度搜索典型例题

题目链接

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

4559613

#include<iostream>#include<string.h>#include<stdio.h>using namespace std;#define N 25char a[N][N];int n, m;int num;int f[4][2] = {{-1, 0}, {1, 0}, {0, 1}, {0, -1}};void fun(int x, int y){    num++;    a[x][y] = '#';    int p, q;    for (int i = 0; i < 4; i++)    {        p = x + f[i][0];        q = y + f[i][1];        if (p > 0 && q > 0 && p <= n && q <= m && a[p][q] == '.')        {            fun(p, q);        }    }}int main(){  //freopen("E:\input.txt", "r", stdin);    int i, j;    while ((scanf("%d%d", &m, &n)) != EOF)    {       getchar();       if (n == 0 && m == 0)       {           break;       }       memset(a, 0, sizeof(a));       int n1, m1;       for (i = 1; i <= n; i++)       {           for (j = 1; j <= m; j++)           {               scanf("%c", &a[i][j]);               if (a[i][j] == '@')               {                   n1 = i;                   m1 = j;               }           }           getchar();       }       num = 0;       fun(n1, m1);       printf("%d\n", num);    }    return 0;}