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Red and Black

Red and Black

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 118 Accepted Submission(s): 92
 
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
 
 
Source
Asia 2004, Ehime (Japan), Japan Domestic
 
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Eddy
#include<bits/stdc++.h>#define N 25using namespace std;int vis[N][N];char mapn[N][N];int dir[4][2]={    {1,0},    {-1,0},    {0,1},    {0,-1},};int cur=0;int n,m;bool ok(int x,int y){    if(x<0||x>=m||y<0||y>=n||vis[x][y]||mapn[x][y]==#)        return false;    return true;}void dfs(int x,int y){    cur++;    for(int i=0;i<4;i++)    {        int fx=x+dir[i][0];        int fy=y+dir[i][1];        if(ok(fx,fy))        {            vis[fx][fy]=1;            dfs(fx,fy);        }    }}int main(){    //freopen("C:\\Users\\acer\\Desktop\\in.txt","r",stdin);    while(scanf("%d%d",&n,&m)!=EOF&&n&&m)    {        memset(vis,0,sizeof vis);        int x,y;        getchar();        for(int i=0;i<m;i++)        {            scanf("%s",mapn[i]);            //cout<<mapn[i]<<endl;            for(int j=0;j<n;j++)            {                if(mapn[i][j]==@)                {                    x=i;                    y=j;                }                //cout<<mapn[i][j];            }            //cout<<endl;        }        cur=0;        vis[x][y]=1;        dfs(x,y);        printf("%d\n",cur);    }    return 0;}

 

Red and Black