ZOJ 2165 POJ 1979 Red and Black DFS水题

Red and Black

Time Limit: 1000MS
Memory Limit: 30000KTotal Submissions: 24766
Accepted: 13359

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) 
The end of the input is indicated by a line consisting of two zeros. 

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

Japan 2004 Domestic

DFS标记统计个数：

#include <stdio.h>#include <string.h>char mp[25][25];bool vis[21][21];int num;int bhx[] = {0,0,1,-1};int bhy[] = {1,-1,0,0};void dfs(int y,int x,int m,int n){    num++;    vis[y][x] = true;    for(int i = 0;i < 4;i++)    {        int fx = x + bhx[i];        int fy = y + bhy[i];        if(fx >= 0 && fx < n && fy >= 0 && fy < m && mp[fy][fx] == '.' && !vis[fy][fx])        {            dfs(fy,fx,m,n);        }    }}int main(){    int n,m;    while(scanf("%d%d",&n,&m),n || m)    {        num = 0;        for(int i = 0;i < m;i++)            scanf("%s",mp[i]);        for(int i = 0;i < m;i++)        {            int j;            for(j = 0;j < n;j++)            {                if(mp[i][j] == '@')                {                    memset(vis,false,sizeof(vis));                    dfs(i,j,m,n);                    break;                }            }            if(j < n)                break;        }        printf("%d\n",num);    }    return 0;}