Strange behavior with Python flood-fill algorithm -

Strange behavior with Python flood-fill algorithm -

i'm implementing flood-fill algorithm python minesweeper.

before show algorithm, allow me define things important:

board, when pretty printed, looks this:

x 1 1 1 3 x 2 1 2 x 2 2 3 x 2 x x 3 1 2 1 1 2 2 1 2 x 3 x 3 2 x 2 2 x x 2 3 4 x 4 x 3 x 1 x 2 1 x 2 3 3 x 2 1 1 1 3 3 2 1 x 2 4 x 4 1 1 x 2 2 3 3 2 x 4 3 1 1 x 1 1 2 3 4 x 3 1 1 1 1 2 3 2 x x 2 2 x x 1 2 3 3 2 2 x x 3 4 x 2 1 x x 2 x 3 3 2 3 3 3 2 1 2 2 x x 4 x 3 2 3 x x 2 1 1 1 3 2 2 1 x 2 x 1 2 x 3 x 4 x x 4 3 1 2 x 3 1 1 2 x 2 2 2 2 1 1 3 x 4 2 3 3 3 x x 3 2 1 1 1 1 1 x 3 1 3 x 2 2 x 2 1 x 1 1 4 x x 1 1 x 2 x 3 1 3 x 2 1 2 2 2 2 2 2 3 x 3 1 2 3 x 2 3 x 2 1 1 1 1 1 1 x 2 2 x 4 x 3 1 1 x 2 x 2 1 1 1 1 2 x 1 1 2 3 x 2 2 x x 2 1 1 1 2 2 1 2 3 x 2 1 1 1 x 2 1 1 1 2 2 2 2 2 1 x 2 1 x x 3 2 1 1 3 3 2 1 1 1 1 1 2 x x 2 x 2 1 2 2 3 x 2 1 x x 2 2 x 1 2 x 3 3 x 2 1 1 1 1 2 1 1 2 x 2 2 3 4 x 2 2 2 4 x 3 1 1 1 1 x 1 1 x 1 2 2 3 2 x 3 2 1 1 x 3 x 2 2 2 2 1 1 1 1 x 2 x 3 x 1 1 1 2 1 1 1 x 1

obviously x's represent mines, , numbers represent number of mines surrounding place. empty spaces mean there no numbers there. board how i'm storing information.

current_board, when pretty printed, looks this:

[a][b][c][d][e][f][g][h][i][j][k][l][m][n][o][p][q][r][s][t][u][v][w][x][y] [1] o o o o o o o o o o o o o o o o o o o o o o o o o [2] o o o o o o o o o o o o o o o o o o o o o o o o o [3] o o o o o o o o o o o o o o o o o o o o o o o o o [4] o o o o o o o o o o o o o o o o o o o o o o o o o [5] o o o o o o o o o o o o o o o o o o o o o o o o o [6] o o o o o o o o o o o o o o o o o o o o o o o o o [7] o o o o o o o o o o o o o o o o o o o o o o o o o [8] o o o o o o o o o o o o o o o o o o o o o o o o o [9] o o o o o o o o o o o o o o o o o o o o o o o o o [10] o o o o o o o o o o o o o o o o o o o o o o o o o [11] o o o o o o o o o o o o o o o o o o o o o o o o o [12] o o o o o o o o o o o o o o o o o o o o o o o o o [13] o o o o o o o o o o o o o o o o o o o o o o o o o [14] o o o o o o o o o o o o o o o o o o o o o o o o o [15] o o o o o o o o o o o o o o o o o o o o o o o o o [16] o o o o o o o o o o o o o o o o o o o o o o o o o [17] o o o o o o o o o o o o o o o o o o o o o o o o o [18] o o o o o o o o o o o o o o o o o o o o o o o o o

the zeros covered cells. board , current_board have same number of rows , columns.

finally,

possible_mine_numbers = ['1','2','3','4','5','6','7','8']

so, when user enters row , column value, eg 1,a, coverted python indexing, (0,0) , passed floodfill algorithm (note print statements used rough debugging).

def floodfill(current_board, row, col): print row print col if board[row][col] in possible_mine_numbers: current_board[row][col] = board[row][col] + ' ' else: if current_board[row][col] != ' ': current_board[row][col] = ' ' if row > 0: print 'a' floodfill(current_board, row - 1, col) if row < len(board[row]) - 1: print 'b' floodfill(current_board, row + 1, col) if col > 0: print 'c' floodfill(current_board, row, col - 1) if col < len(board) - 1: print 'd' floodfill(current_board, row, col + 1)

now, algorithm works fine in position other bottom row of board (row 17). when seek run on bottom row, illustration 18, e (17, 4) next output (due debugging) (look @ lastly 3):

17 4 16 4 15 4 14 4 16 4 b 15 3 c 15 5 d 17 4 b 16 3 c 16 5 d 18 4

it says 'a', 18, , 4! reason floodfill algorithm jumping 16 18 on first if branch. makes absolutely no sense me , i'm not sure why i'm getting unusual behavior. if @ rest of output, can see jumping 2 row indices @ points.

can see wrong algorithm?

you're saying if row < len(board[row]) comparing row index length of row (i.e. number of columns) not number of rows. similarly, you're comparing col, column index, len(board), len(board) certainly number of rows, not number of columns.

python algorithm list flood-fill minesweeper