HDU 1312 Red and Black(DFS)

Red and Black

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 21605    Accepted Submission(s): 13157

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 <stdio.h>char map[50][50];int set[4][2]={{1,0},{-1,0},{0,1},{0,-1}};int m,n;int max;void dfs(int x,int y){    if(x<0||y<0||x>=n||y>=m)return;    max++;    for(int i=0;i<4;i++)    {        if(map[x+set[i][0]][y+set[i][1]]!='#')        {            map[x+set[i][0]][y+set[i][1]]='#';            dfs(x+set[i][0],y+set[i][1]);            }    }    return;}int main(int argc, char *argv[]){        while(scanf("%d %d",&m,&n),m+n)    {        int i,j,si,sj;        getchar();        for(i=0;i<n;i++)        {            for(j=0;j<m;j++)            {                    scanf("%c",&map[i][j]);                if(map[i][j]=='@')                {                    si=i;                    sj=j;                }            }            getchar();        }        map[si][sj]='#';        max=0;        dfs(si,sj);        printf("%d\n",max);    }    return 0;}