Red and Black
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
题目链接：
题意描述：
给你一个迷宫图，设定“@”为起点，然后“#”为障碍物，“.”为可行路，问从“@”出发最多能连通多少个“."
解题思路：
把这些字符存到一个矩阵里，然后从“@”dfs搜索，定义一个count记录点的个数
程序代码：
#include<stdio.h>
#include<string.h>
char str[25][25];
int m,n,count;
void dfs(int x,int y);
int main()
{
int i,j;
while(scanf("%d%d",&n,&m),m!=0||n!=0)
{
count=0;
for(i=0;i<m;i++)
scanf("%s",str[i]);
for(i=0;i<m;i++)
for(j=0;j<n;j++)
if(str[i][j]=='@')
dfs(i,j);//此处没有break，因为费不了几步
printf("%d\n",count);
}
return 0;
}
void dfs(int x,int y)
{
int tx,ty,i;
int next[4][2]={0,1, 0,-1, 1,0, -1,0};
str[x][y]='#';
count++;
for(i=0;i<4;i++)
{
tx=x+next[i][0];
ty=y+next[i][1];
if(tx<0||tx>=m||ty<0||ty>=n)
continue;
if(str[tx][ty]=='.')
dfs(tx,ty);
}
}