图深度遍历的一题

本文章原发于博客园，其他可能是本人的日志同步

问题：

　　输入一个n*n的方块，统计连块的个数，连块就是有公共的边或者顶点

代码：

mat = []
def init_mat(n):
    for i in range(0,n+2):
        # add the edge of the mat
        mat.append([0] * (n+2))
    define_mat(n+1)

def define_mat(n):
    c = 0
    stop = 'n'
    while stop != 'y':
        row = input("row?: ")
        col = input("col?: ")
        mat[row][col] = -1
        stop = raw_input("stop?: ")

    for i in range(1, n):
        for j in range(1, n):
            if mat[i][j] == -1:
                c = c + 1
                dfs(i, j, c, n)

    for i in range(1, n):
        print mat[i][1:n]

def dfs(i, j, c, n):
    # eight ways (i+1, j) (i-1,j)  (i, j+1)  (i, j-1)  (i-1,j-1)  (i-1, j+1)  (i+1, j-1) (i+1, j+1)
    if mat[i][j] == -1 and 0 < i < n and 0 < j < n:
        mat[i][j] = c
        dfs(i+1, j, c, n)
        dfs(i+1, j, c, n)
        dfs(i-1,j, c, n)
        dfs(i, j+1, c, n)
        dfs(i, j-1, c, n)
        dfs(i-1,j-1, c, n)
        dfs(i-1, j+1, c, n)
        dfs(i+1, j-1, c, n)
        dfs(i+1, j+1, c, n)
    else:
        return c