POJ 1979 Red and Black(DFS 连通块中元素数量)

标签：acm   王桂平   图论   

题意  求矩阵中包含‘@’的‘.‘连通块中元素数量  ‘@‘也看做‘.‘ 

最基础的dfs了

#include<cstdio>
#include<cstring>
using namespace std;
const int N = 30;
char mat[N][N];
int dx[4] = {0, 0, -1, 1}, dy[4] = { -1, 1, 0, 0};
int ans;

void dfs(int r, int c)
{
    if(mat[r][c] != '.') return;
    mat[r][c] = '#';
    for(int i = 0; i < 4; ++i)
    {
        int x = r + dx[i], y = c + dy[i];
        if(mat[x][y] == '.')
        {
            dfs(x, y);
            ++ans;
        }
    }
}

int main()
{
    int m, n, sx, sy;
    while(scanf("%d%d", &m, &n), m)
    {
        memset(mat, 0, sizeof(mat));
        for(int i = 1; i <= n; ++i)
            scanf("%s", mat[i] + 1);
        for(int i = 1; i <= n; ++i)
            for(int j = 1; j <= m; ++j)
                if(mat[i][j] == '@') sx = i, sy = j;
        ans = 1;
        dfs(sx, sy);
        printf("%d\n", ans);
    }
}

Description

Input

Output

Sample Input

6 9
....#.
.....#
......
......
......
......
......
#@...#
.#..#.
11 9
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
0 0

Sample Output

45
59
6
13

POJ 1979 Red and Black(DFS 连通块中元素数量)

标签：acm   王桂平   图论   

原文地址：http://blog.csdn.net/acvay/article/details/40042183