PYTHON DFS 无限循环

Question

Im trying to implement dfs on a matrix but inside my while loop in cases the goal is unreachable it never exists the loop. Any ideas how to tackle that? Some pointers for the code: RowCol and RowNum have indices of reachable neighbours(ie right, down,right diagonal down)I am adding that to the indices of the current node to get the neighbours indices. If it's not visited or an obstacle(equal to 1) add it to stack and repeat.

    while stack:

    curr = stack.get()  # Dequeue the front cell
    path.append(curr.pt)
    # If we have reached the destination cell,
    # we are done
    pt = curr.pt
    if pt == goal:
        print("Sequence  : ")
        print(path)
        print("Path : ")
        print(curr.path+" to "+str(pt))
        return curr.dist

    # Otherwise enqueue its adjacent cells
    for i in range(3):
        if i == 0 or i == 1:
            cost = 2
        elif i == 2:
            cost = 3
        row = pt[0] + rowNum[i]
        col = pt[1] + colNum[i]

        # if adjacent cell is valid, has path
        # and not visited yet, enqueue it.
        if isValid(row, col):
            if matrix[row][col] == "0" and not visited[row][col]:
                visited[row][col] = True
                Adjcell = queueNode([row, col], curr.dist + cost,curr.path+" to "+str(curr.pt))
                stack.put(Adjcell)

# Return -1 if destination cannot be reached
print(matrix[start[0]][start[1]])
print(matrix[goal[0]][goal[1]])
print("Can't reach goal")
return -1

Answer 1

如果你想循环使用

while True :