Problem:


Score : 400 points

Problem Statement

Takahashi has a maze, which is a grid of H \times W squares with H horizontal rows and W vertical columns.

The square at the i-th row from the top and the j-th column is a "wall" square if S_{ij} is #, and a "road" square if S_{ij} is ..

From a road square, you can move to a horizontally or vertically adjacent road square.

You cannot move out of the maze, move to a wall square, or move diagonally.

Takahashi will choose a starting square and a goal square, which can be any road squares, and give the maze to Aoki.

Aoki will then travel from the starting square to the goal square, in the minimum number of moves required.

In this situation, find the maximum possible number of moves Aoki has to make.

Constraints

1 \leq H,W \leq 20

S_{ij} is . or #.

S contains at least two occurrences of ..

Any road square can be reached from any road square in zero or more moves.

Input

Input is given from Standard Input in the following format:

H W
S_{11}...S_{1W}
:
S_{H1}...S_{HW}

Output

Print the maximum possible number of moves Aoki has to make.

Sample Input 1

3 3
...
...
...

Sample Output 1

4

If Takahashi chooses the top-left square as the starting square and the bottom-right square as the goal square, Aoki has to make four moves.

Sample Input 2

3 5
...#.
.#.#.
.#...

Sample Output 2

10

If Takahashi chooses the bottom-left square as the starting square and the top-right square as the goal square, Aoki has to make ten moves.



Sample input:
3 3
...
...
...


Sample output:
4

Submission status: Time Limit Exceeded

Solution code:
from array import array

h, w = map(int, input().split())
maze = []
for i in range(h):
    maze.append(input())

g = []

for i in range(w * h):
    g.append(array('l', [10000000] * (w * h)))

for i in range(w * h):
    g[i][i] = 0

for i in range(h):
    for j in range(w):
        if maze[i][j] == '#':
            continue
        if maze[i][j] == '.':
            if i > 0 and maze[i-1][j] != '#':
                g[i * w + j][(i-1) * w + j] = 1
                g[(i-1) * w + j][i * w + j] = 1
            if i < h-1 and maze[i+1][j] != '#':
                g[i * w + j][(i+1) * w + j] = 1
                g[(i+1) * w + j][i * w + j] = 1
            if j > 0 and maze[i][j-1] != '#':
                g[i * w + j][i * w + j-1] = 1
                g[i * w + j-1][i * w + j] = 1
            if j < w-1 and maze[i][j+1] != '#':
                g[i * w + j][i * w + j+1] = 1
                g[i * w + j+1][i * w + j] = 1

def floyed(g, h, w):
    for k in range(h*w):
        for i in range(h*w):
            for j in range(h*w):
                if i == j or i == k or k == j:
                    continue
                if g[i][j] > g[i][k] + g[k][j]:
                    g[i][j] = g[i][k] + g[k][j]

floyed(g,h,w)
result = 0

for i in range(w*h):
    for j in range(w*h):
        if g[i][j] < 10000000:
            if g[i][j] > result:
                result = g[i][j]

print(result)

Submission status: Time Limit Exceeded

Solution code:
import queue

h, w = map(int, input().split(" "))

s = list()
for l in range(0, h):
    line = input()
    s.append(line)

dx = {(1, 0), (-1, 0), (0, 1), (0, -1)}


def search(start_h, start_w):
    if s[start_h][start_w] == "#":
        return -1

    cost = [[10000000 for i in range(0, w)] for j in range(0, h)]

    q = queue.Queue()
    q.put((start_h, start_w, 0))
    cost[start_h][start_w] = 0
    while not q.empty():
        current_h, current_w, current_c = q.get()

        # print("pos_w:%d, pos_h:%d, cost:%d" % (current_w, current_h, current_c))
        for dw, dh in dx:
            next_h = current_h + dh
            next_w = current_w + dw
            next_c = current_c + 1

            if next_h < 0 or next_h >= h or next_w < 0 or next_w >= w:
                continue

            if s[next_h][next_w] == "#" or cost[next_h][next_w] < next_c:
                continue
            else:
                q.put((next_h, next_w, next_c))
                cost[next_h][next_w] = next_c

    tmp = 0
    for a in range(0, w):
        for b in range(0, h):
            if cost[b][a] > 1000:
                continue
            else:
                tmp = max(tmp, cost[b][a])

    return tmp


ans = 0
for i in range(0, w):
    for j in range(0, h):
        # print("start_h:%d, start_w:%d" % (j, i))
        cost_tmp = search(j, i)
        ans = max(ans, cost_tmp)
        # print("start_h:%d, start_w:%d cost:%d" % (j, i, cost_tmp))


print(ans)

Submission status: Time Limit Exceeded

Solution code:
import sys
from collections import deque

read = sys.stdin.read
readline = sys.stdin.readline

H, W = map(int, readline().split())
S = tuple(read().split())


def bfs(grid, start):
    distance = [[0] * W for _ in range(H)]
    queue = deque([start])
    visited = [[False] * W for _ in range(H)]
    while queue:
        x, y = queue.popleft()
        visited[x][y]=True

        for i, j in ([1, 0], [-1, 0], [0, 1], [0, -1]):
            new_y, new_x = y + j, x + i
            if 0 <= new_y < W and 0 <= new_x < H:
                if grid[new_x][new_y] == '.' and not visited[new_x][new_y]:
                    distance[new_x][new_y] = distance[x][y] + 1
                    queue.append((new_x, new_y))
    return distance


answer = 0
for i in range(H):
    for j in range(W):
        if S[i][j] == '#':
            continue

        cnt = 0
        for dx, dy in ([1, 0], [-1, 0], [0, 1], [0, -1]):
            new_y, new_x = dy + j, dx + i
            if 0 <= new_y < W and 0 <= new_x < H:
                if S[new_x][new_y] == '.':
                    cnt += 1

        if cnt > 2:
            continue

        tmp = max(map(max, bfs(S, (i, j))))
        if tmp > answer:
            answer = tmp

print(answer)

Submission status: Time Limit Exceeded

Solution code:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools
from collections import deque

sys.setrecursionlimit(10**7)
inf = 10**20
mod = 10**9 + 7

DR = [1, -1, 0, 0]
DC = [0, 0, 1, -1]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()

def solve(maze, st_tuple, g_tuple):
    st_row, st_col = st_tuple
    g_row, g_col = g_tuple
    W, H = len(maze[0]), len(maze)
    visited = [[0 for _ in range(W)] for __ in range(H)]
    q = deque()
    q.append((st_row, st_col, 0))
    while q:
        cur_row, cur_col, count = q.popleft()
        if cur_row == g_row and cur_col == g_col:
            return count
        for dr, dc in zip(DR, DC):
            next_row = cur_row + dr
            next_col = cur_col + dc
            if 0 <= next_row < H and 0 <= next_col < W:
                pass
            else:
                continue
            if maze[next_row][next_col] == '#':
                continue
            if visited[next_row][next_col]:
                continue
            q.append((next_row, next_col, count + 1))
            visited[next_row][next_col] = 1
    return -1

def main():
    H, W = LI()
    maze = []
    for _ in range(H):
        maze.append(S())
    num = 0
    seen = set()
    axes = [(s_r, s_c, g_r, g_c) for s_r in range(H) for s_c in range(W) for g_r in range(H) for g_c in range(W)]
    for st_row, st_col, g_row, g_col in axes:
        if maze[st_row][st_col] == '#' or maze[g_row][g_col] == '#':
            continue
        if ((st_row, st_col, g_row, g_col)) in seen:
            continue
        if ((g_row, g_col, st_row, st_col)) in seen:
            continue
        a = solve(maze, (st_row, st_col), (g_row, g_col))
        seen.add((st_row, st_col, g_row, g_col))
        num = max(num, a)
    '''
    for st_row in range(H):
        for st_col in range(W):
            for g_row in range(H):
                for g_col in range(W):
    '''


    print(num)
main()

Submission status: Time Limit Exceeded

Solution code:
h, w = map(int, input().split())
maze = []
for i in range(h):
    maze.append(list(input()))

import collections
#print(dat)
def clear_maze(sx, sy, gx, gy):
    INF = 100000000
    field_x_length = len(maze)
    field_y_length = len(maze[0])
    distance = [[INF for i in range(40)] for j in range(40)]
    def bfs():
        queue = collections.deque([])
        queue.appendleft((sx, sy))
        distance[sx][sy] = 0
        while len(queue):
            x, y = queue.pop()
            if x == gx and y == gy:
                break
            #print("seek {0} {1}".format(x, y))
            for i in range(0, 4):
                nx, ny = x + [1, 0, -1, 0][i], y + [0, 1, 0, -1][i]
                if (0 <= nx and nx < field_x_length and 0 <= ny and ny < field_y_length and maze[nx][ny] != '#' and distance[nx][ny] == INF):
                    queue.appendleft((nx, ny))
                    distance[nx][ny] = distance[x][y] + 1
        return distance[gx][gy]
    return bfs()

res = -1
for yy in range(0, h):
    for xx in range(0, w):
        if maze[yy][xx] == "#":
            continue
        for yyy in range(yy, h):
            for xxx in range(0, w):
                if maze[yyy][xxx] == "#":
                    continue
                step = clear_maze(yy, xx, yyy, xxx)
                #print("s={0},{1} g={2},{3} cost = {4}".format(xx,yy,xxx,yyy,step))
                if step == 100000000:
                    continue
                res = max(res, step)
print(res)

Submission status: Time Limit Exceeded

Solution code:
from collections import deque


# (sx, sy) から (gx, gy) への最短距離を求める
# 辿り着けないと INF
def bfs():
    # すべての点を INF で初期化
    #d = [[10 ** 12] * w for i in range(h)]
    d = []
    for i in range(h):
        d.append([10 ** 12] * w)

    # 移動4方向のベクトル
    dx = [1, 0, -1, 0]
    dy = [0, 1, 0, -1]

    # スタート地点をキューに入れ、その点の距離を0にする
    que = deque([])
    que.append((sx, sy))
    d[sx][sy] = 0

    # キューが空になるまでループ
    while que:
        # キューの先頭を取り出す
        p = que.popleft()
        # 取り出してきた状態がゴールなら探索をやめる
        if p[0] == gx and p[1] == gy:
            break
        # 移動4方向をループ
        for i in range(4):
            # 移動した後の点を (nx, ny) とする
            nx = p[0] + dx[i]
            ny = p[1] + dy[i]

            # 移動が可能かの判定とすでに訪れたことがあるかの判定
            # d[nx][ny] != INF なら訪れたことがある
            if 0 <= nx < h and 0 <= ny < w and maze[nx][ny] != "#" and d[nx][ny] == 10 ** 12:
                # 移動できるならキューに入れ、その点の距離を p からの距離 +1 で確定する
                que.append((nx, ny))
                d[nx][ny] = d[p[0]][p[1]] + 1

    return d[gx][gy]


def solve():
    INF = h*w*2
    mem = [[INF for j in range(w)] for i in range(h)]
    mem[sy][sx] = 0
    q = deque()
    q.append((sy,sx))
    while len(q):
        y,x = q.popleft()
        for y2,x2 in [(y,x-1),(y-1,x),(y,x+1),(y+1,x)]:
            if not 0 <= y2 < h or not 0 <= x2 < w or maze[y2][x2] == '#' or mem[y2][x2] < INF: continue
            mem[y2][x2] = mem[y][x] + 1
            if y2 == gy and x2 == gx:
                return mem[y2][x2]
                break
            q.append((y2,x2))

    return mem[gy][gx]
            

h, w = map(int, input().split())
maze = [list(input()) for i in range(h)]

ans = 0
for sy in range(h):
    for sx in range(w):
        if maze[sy][sx] == ".":
            for gy in range(h):
                for gx in range(w):
                    if sx == gx and sy == gy:
                        continue
                    if maze[gy][gx] == ".":
                        ans = max(ans, solve())

print(ans)

Submission status: Time Limit Exceeded

Solution code:
from collections import deque

H, W = map(int, input().split())
S = [list(input()) for _ in range(H)]

# ある地点を渡すと、その地点から到達可能かつ距離未計算の地点のリストを返す
def not_investigated_positions(current_position):
    output = []
    for udrl in [[0, 1], [0, -1], [1, 0], [-1, 0]]:
        y = current_position[0]+udrl[0]
        x = current_position[1]+udrl[1]
        if 0 <= y <= H-1 and 0 <= x <= W-1:
            if S[y][x] == "." and distance[y][x] == -1:
                output.append([y, x])
    return output

ans = 0
for sy in range(H):
    for sx in range(W):
        for gy in range(H):
            for gx in range(W):
                if S[sy][sx] == "#" or S[gy][gx] == "#":
                    continue
                distance = [[-1]*W for _ in range(H)]
                current_position = [sy, sx]
                distance[sy][sx] = 0
                next_positions = deque()
                next_positions.append(current_position)

                while next_positions and current_position != [gy, gx]:
                    current_position = next_positions.popleft()
                    for q in not_investigated_positions(current_position):
                        distance[q[0]][q[1]] = distance[current_position[0]][current_position[1]] + 1
                        next_positions.append(q)

                ans = max(ans, distance[gy][gx])

print(ans)

Submission status: Time Limit Exceeded

Solution code:
from copy import deepcopy
from collections import deque
from itertools import product

H, W = map(int, input().split())
S = [list(input()) for i in range(H)]

S = [[1000000 if s == '.' else '#' for s in row] for row in S]
ans = 0
for i, j in product(range(H), range(W)):
    if S[i][j] == '#':
        continue
    d = deepcopy(S)
    d[i][j] = 0
    v = [[False] * W for i in range(H)]
    q = deque([(i, j)])
    while len(q) > 0:
        x, y = q.popleft()
        v[x][y] = True
        if 0 <= x - 1 and S[x - 1][y] != '#':
            d[x - 1][y] = min(d[x][y] + 1, d[x - 1][y])
            if not v[x - 1][y]:
                q.append((x - 1, y))
        if x + 1 < H and S[x + 1][y] != '#':
            d[x + 1][y] = min(d[x][y] + 1, d[x + 1][y])
            if not v[x + 1][y]:
                q.append((x + 1, y))
        if 0 <= y - 1 and S[x][y - 1] != '#':
            d[x][y - 1] = min(d[x][y] + 1, d[x][y - 1])
            if not v[x][y - 1]:
                q.append((x, y - 1))
        if y + 1 < W and S[x][y + 1] != '#':
            d[x][y + 1] = min(d[x][y] + 1, d[x][y + 1])
            if not v[x][y + 1]:
                q.append((x, y + 1))
    for x, y in product(range(H), range(W)):
        if v[x][y]:
            ans = max(d[x][y], ans)
print(ans)

Submission status: Time Limit Exceeded

Solution code:
from collections import deque
H, W = map(int, input().split())
c = ["#"*(W+2)] + ["#" + input() + "#" for _ in range(H)] + ["#"*(W+2)]


def bfs(start):
	queue = deque([start])
	visited = [[False for _ in range(W+2)] for _ in range(H+2)]
	tekazu = [[0 for _ in range(W+2)] for _ in range(H+2)]
	num = 0
	while queue:

		label = queue.pop()
		
		if label not in visited:
			visited.append(label)
			#print(visited)
			if c[label[0] + 1][label[1]] == "." and [label[0] + 1, label[1]] not in visited:
				queue.appendleft([label[0] + 1, label[1]])
				tekazu[label[0] + 1][label[1]] = tekazu[label[0]][label[1]] + 1
				num = max(num, tekazu[label[0] + 1][label[1]])

			if c[label[0] - 1][label[1]] == "." and [label[0] - 1, label[1]] not in visited:
				queue.appendleft([label[0] - 1, label[1]])
				tekazu[label[0] - 1][label[1]] = tekazu[label[0]][label[1]] + 1
				num = max(num, tekazu[label[0] - 1][label[1]])

			if c[label[0]][label[1] + 1] == "." and [label[0], label[1] + 1] not in visited:
				queue.appendleft([label[0], label[1] + 1])
				tekazu[label[0]][label[1] + 1] = tekazu[label[0]][label[1]] + 1
				num = max(num, tekazu[label[0]][label[1] + 1])

			if c[label[0]][label[1] - 1] == "." and [label[0], label[1] - 1] not in visited:
				queue.appendleft([label[0], label[1] - 1])
				tekazu[label[0]][label[1] - 1] = tekazu[label[0]][label[1]] + 1
				num = max(num, tekazu[label[0]][label[1] - 1])

	return num

ans = 0
for h in range(1, H+1):
	for w in range(1, W+1):
		if c[h][w] == ".":
			ans = max(ans, bfs([h, w]))
print(ans)

Submission status: Time Limit Exceeded

Solution code:
h, w = map(int, input().split())
dat = []
for i in range(h):
    dat.append(list(input()))

import collections
#print(dat)
def clear_maze(sx, sy, gx, gy, maze):
    INF = 100000000
    field_x_length = len(maze)
    field_y_length = len(maze[0])
    distance = [[INF for i in range(40)] for j in range(40)]
    def bfs():
        queue = collections.deque([])
        queue.appendleft((sx, sy))
        distance[sx][sy] = 0
        while len(queue):
            x, y = queue.pop()
            if x == gx and y == gy:
                break
            #print("seek {0} {1}".format(x, y))
            for i in range(0, 4):
                nx, ny = x + [1, 0, -1, 0][i], y + [0, 1, 0, -1][i]
                if (0 <= nx and nx < field_x_length and 0 <= ny and ny < field_y_length and maze[nx][ny] != '#' and distance[nx][ny] == INF):
                    queue.appendleft((nx, ny))
                    distance[nx][ny] = distance[x][y] + 1
        return distance[gx][gy]
    return bfs()

res = -1
for yy in range(0, h):
    for xx in range(0, w):
        if dat[yy][xx] == "#":
            continue
        for yyy in range(yy, h):
            for xxx in range(0, w):
                if dat[yyy][xxx] == "#":
                    continue
                step = clear_maze(yy, xx, yyy, xxx, dat)
                #print("s={0},{1} g={2},{3} cost = {4}".format(xx,yy,xxx,yyy,step))
                if step == 100000000:
                    continue
                res = max(res, step)
print(res)

Submission status: Time Limit Exceeded

Solution code:
import queue
import sys

input = sys.stdin.readline


class Solution:
    def main(self):
        H, W = map(int, input().split())
        S = [list(input().rstrip()) for _ in range(H)]

        for i in range(H):
            S[i] = ["#"] + S[i] + ["#"]
        S = [["#"] * (W + 2)] + S + [["#"] * (W + 2)]

        ans = 0
        for i in range(1, H + 1):
            for j in range(1, W + 1):
                if S[i][j] == "#":
                    continue
                for n in range(1, H + 1):
                    for m in range(1, W + 1):
                        if S[n][m] == "#":
                            continue
                        v = self.min_move(S, (i, j), (n, m))
                        ans = max(ans, v)
        print(ans)

    def min_move(self, map, start, goal):
        moving_range = ((1, 0), (-1, 0), (0, 1), (0, -1))

        q = queue.Queue()
        q.put((start, 0))

        while q:
            pos, cnt = q.get()
            if pos == goal:
                return cnt

            for move in moving_range:
                i, j = pos[0] + move[0], pos[1] + move[1]
                if map[i][j] == ".":
                    q.put(((i, j), cnt + 1))


# Run main
if __name__ == '__main__':
    Solution().main()

Submission status: Time Limit Exceeded

Solution code:
import sys
from collections import deque

read = sys.stdin.read
readline = sys.stdin.readline

H, W = map(int, readline().split())
S = tuple(read().split())


def bfs(grid, start):
    distance = [[0] * W for _ in range(H)]
    queue = deque([start])
    visited = set()
    while queue:
        x, y = queue.popleft()
        visited.add((x, y))

        for i, j in ([1, 0], [-1, 0], [0, 1], [0, -1]):
            new_y, new_x = y + j, x + i
            if 0 <= new_y < W and 0 <= new_x < H:
                if grid[new_x][new_y] == '.' and (new_x, new_y) not in visited:
                    distance[new_x][new_y] = distance[x][y] + 1
                    queue.append((new_x, new_y))
    return distance


answer = 0
for i in range(H):
    for j in range(W):
        if S[i][j] == '#':
            continue

        cnt = 0
        for dx, dy in ([1, 0], [-1, 0], [0, 1], [0, -1]):
            new_y, new_x = dy + j, dx + i
            if 0 <= new_y < W and 0 <= new_x < H:
                if S[new_x][new_y] == '.':
                    cnt += 1

        if cnt > 2:
            continue

        tmp = max(map(max, bfs(S, (i, j))))
        if tmp > answer:
            answer = tmp

print(answer)

Submission status: Time Limit Exceeded

Solution code:
def C_BFS(R, C, sy, sx, gy, gx, c):
    """
    R:行数
    C:列数
    sy,sx:スタートの座標(sy行sx列)
    gy,gx:ゴールの座標(gy行gx列)
    c:迷路の形状(.:通路,#:壁)
    """
    INF = float('inf')
    sy -= 1
    sx -= 1
    gy -= 1
    gx -= 1
 
    def bfs(maze, row, column, sy, sx, gy, gx):
        # 原点は(0,0)とする(問題の制約によっては原点をずらす必要がある)
        queue = []
        queue.insert(0, (sy, sx))
        dist = [[INF for _ in range(column)] for _ in range(row)]
        dist[sy][sx] = 0  # yが行数、xが列数を意味するときはこの順に書く
        while len(queue):
            y, x = queue.pop()
            if x == gx and y == gy:
                # ゴール座標と一致するなら
                break
            for i in range(4):
                nx, ny = x + [1, 0, -1, 0][i], y + \
                    [0, 1, 0, -1][i]  # (x,y)の右、上、左、下
                if 0 <= nx and nx < column and 0 <= ny and ny < row \
                        and maze[ny][nx] != '#' and dist[ny][nx] == INF:
                    #(nx,ny)が迷路内であり、壁でなく、まだ距離が確定していないとき
                    queue.insert(0, (ny, nx))  # 次に探索する座標
                    dist[ny][nx] = dist[y][x] + 1
        return dist[gy][gx]
 
    maze = [['' for _ in range(C)] for _ in range(R)]
    for i, tmp in enumerate(c):
        for j in range(C):
            maze[i][j] = tmp[j]
 
    ans = bfs(maze, R, C, sy, sx, gy, gx)
    return ans

R , C = [int(i) for i in input().split()]
c = [input() for _ in range(R)]

ans = 0
for sy in range(1, R+1):
    for sx in range(1, C+1):
        if c[sy-1][sx-1] != '#':
            for gy in range(1, R+1):
                for gx in range(1, C+1):
                    if c[gy-1][gx-1] != '#':
                        count_tmp = C_BFS(R, C, sy, sx, gy, gx, c)
                        if ans < count_tmp:
                            ans = count_tmp
print(ans)

Submission status: Time Limit Exceeded

Solution code:
# -*- coding: utf-8 -*-
from collections import deque
h,w = map(int, input().split())
s = [input() for _ in range(h)]

if h==1 and w==1:
    print(0)
    exit()

def solve(sh,sw,gh,gw):
    if s[sh][sw]=="#" or s[gh][gw]=="#":
        return -1

    visited = [[False for _ in range(w)] for _ in range(h)]
    visited[sh][sw] = True
    q = deque([(sh,sw,0)])
    while len(q)>0:
        hi,wi,r = q.popleft()
        for dh,dw in [[1,0],[0,1],[-1,0],[0,-1]]:
            if hi+dh>=0 and hi+dh<h and wi+dw>=0 and wi+dw<w and s[hi+dh][wi+dw]==".":
                if hi+dh==gh and wi+dw==gw:
                    return r+1
                elif not visited[hi+dh][wi+dw]:
                    visited[hi+dh][wi+dw] = True
                    q.append((hi+dh,wi+dw,r+1))

    return -1

res = -1
for shi in range(h):
    for swi in range(w):
        if s[shi][swi]=="#":
            continue
        for ghi in range(h):
            for gwi in range(w):
                if shi>=ghi and swi>=gwi:
                    continue
                r = solve(shi,swi,ghi,gwi)
                res = max(res, r)

print(res)

Submission status: Time Limit Exceeded

Solution code:
import queue

h, w = map(int, input().split(" "))

s = list()
for l in range(0, h):
    line = input()
    s.append(line)

dx = {(1, 0), (-1, 0), (0, 1), (0, -1)}


def search(start_h, start_w):
    if s[start_h][start_w] == "#":
        return -1

    cost = [[10000000 for i in range(0, w)] for j in range(0, h)]

    q = queue.Queue()
    q.put((start_h, start_w, 0))
    while not q.empty():
        current_h, current_w, current_c = q.get()
        if cost[current_h][current_w] < 10000000:
            continue
        else:
            cost[current_h][current_w] = current_c

        # print("pos_w:%d, pos_h:%d, cost:%d" % (current_w, current_h, current_c))
        for dw, dh in dx:
            next_h = current_h + dh
            next_w = current_w + dw
            next_c = current_c + 1

            if next_h < 0 or next_h >= h or next_w < 0 or next_w >= w:
                continue

            if s[next_h][next_w] == "#" or cost[next_h][next_w] < next_c:
                continue
            else:
                q.put((next_h, next_w, next_c))

    tmp = 0
    for a in range(0, w):
        for b in range(0, h):
            if cost[b][a] > 1000:
                continue
            else:
                tmp = max(tmp, cost[b][a])

    return tmp


ans = 0
for i in range(0, w):
    for j in range(0, h):
        # print("start_h:%d, start_w:%d" % (j, i))
        cost_tmp = search(j, i)
        ans = max(ans, cost_tmp)
        # print("start_h:%d, start_w:%d cost:%d" % (j, i, cost_tmp))


print(ans)

Submission status: Time Limit Exceeded

Solution code:
h, w = map(int, input().split())
dat = []
for i in range(h):
    dat.append(list(input()))

#print(dat)
def clear_maze(sx, sy, gx, gy, maze):
    INF = 100000000
    field_x_length = len(maze)
    field_y_length = len(maze[0])
    distance = [[INF for i in range(40)] for j in range(40)]
    def bfs():
        queue = []
        queue.insert(0, (sx, sy))
        distance[sx][sy] = 0
        while len(queue):
            x, y = queue.pop()
            if x == gx and y == gy:
                break
            #print("seek {0} {1}".format(x, y))
            for i in range(0, 4):
                nx, ny = x + [1, 0, -1, 0][i], y + [0, 1, 0, -1][i]
                if (0 <= nx and nx < field_x_length and 0 <= ny and ny < field_y_length and maze[nx][ny] != '#' and distance[nx][ny] == INF):
                    queue.insert(0, (nx, ny))
                    distance[nx][ny] = distance[x][y] + 1
        return distance[gx][gy]
    return bfs()

res = -1
for yy in range(0, h):
    for xx in range(0, w):
        if dat[yy][xx] == "#":
            continue
        for yyy in range(yy, h):
            for xxx in range(0, w):
                if dat[yyy][xxx] == "#":
                    continue
                step = clear_maze(yy, xx, yyy, xxx, dat)
                #print("s={0},{1} g={2},{3} cost = {4}".format(xx,yy,xxx,yyy,step))
                if step == 100000000:
                    continue
                res = max(res, step)
print(res)

Submission status: Time Limit Exceeded

Solution code:
from collections import deque
import itertools
import copy

H, W = map(int, input().split())
S = [list(input()) for _ in range(H)]


def bfs(maze, s, g):
    q = deque()
    q.append((s, 0))

    maze[s[0]][s[1]] = "#"

    while len(q) > 0:
        p, depth = q.popleft()

        if p == g:
            return depth

        # ikerutoko
        next_pos = []
        if 0 <= p[0] - 1 < H and maze[p[0] - 1][p[1]] != "#":
            next_pos.append((p[0] - 1, p[1]))
        if 0 <= p[0] + 1 < H and maze[p[0] + 1][p[1]] != "#":
            next_pos.append((p[0] + 1, p[1]))
        if 0 <= p[1] - 1 < W and maze[p[0]][p[1] - 1] != "#":
            next_pos.append((p[0], p[1] - 1))
        if 0 <= p[1] + 1 < W and maze[p[0]][p[1] + 1] != "#":
            next_pos.append((p[0], p[1] + 1))

        # print(next_pos, q)

        for pos in next_pos:
            maze[pos[0]][pos[1]] = "#"
            q.append((pos, depth + 1))

    return -1


kaisuu = 0
for s in itertools.product(range(H), range(W)):
    for g in itertools.product(range(H), range(W)):
        if s == g or S[s[0]][s[1]] == "#" or S[g[0]][g[1]] == "#":
            continue

        maze = copy.deepcopy(S)
        k = bfs(maze, s, g)
        kaisuu = max(kaisuu, k)

print(kaisuu)

Submission status: Time Limit Exceeded

Solution code:
from collections import deque
import copy
def solve(maze, start, end):
  memo = []
  q = deque()
  q.append([start,[]])
  ans = 0
  while q:
    cur, path = q.popleft()
    if cur == end:
      ans = path
      break
    elif cur in memo:
      continue
    else:
      memo.append(cur)
      for y, x in zip((0,0,1,-1),(1,-1,0,0)):
        if maze[cur[0]+y][cur[1]+x] == ".":
          q.append([[cur[0]+y,cur[1]+x],copy.deepcopy(path)+[cur]])
  return ans


H, W = map(int, input().split())
Maze = [["#"]*(W+2)]+[["#"]+list(input())+["#"] for _ in range(H)] + [["#"]*(W+2)]
Ans = 0
for sy in range(1, H+1):
  for sx in range(1, W+1):
    if Maze[sy][sx] == "#":
      continue
    memo = [[False]*(W+2) for _ in range(H+2)]
    for ey in range(sy, H+1):
      for ex in range(1, W+1):
        if Maze[ey][ex] == "#" or memo[ey][ex]:
          continue
        P = solve(Maze, [sy, sx], [ey,ex])
        Ans = max(Ans, len(P))
        for p in P:
          memo[p[0]][p[1]] = True
print(Ans)

Submission status: Time Limit Exceeded

Solution code:
h, w = map(int, input().split())
dat = []
for i in range(h):
    dat.append(list(input()))

#print(dat)
def clear_maze(sx, sy, gx, gy, maze):
    INF = 100000000
    field_x_length = len(maze)
    field_y_length = len(maze[0])
    distance = [[INF for i in range(40)] for j in range(40)]
    def bfs():
        queue = []
        queue.insert(0, (sx, sy))
        distance[sx][sy] = 0
        while len(queue):
            x, y = queue.pop()
            if x == gx and y == gy:
                break
            #print("seek {0} {1}".format(x, y))
            for i in range(0, 4):
                nx, ny = x + [1, 0, -1, 0][i], y + [0, 1, 0, -1][i]
                if (0 <= nx and nx < field_x_length and 0 <= ny and ny < field_y_length and maze[nx][ny] != '#' and distance[nx][ny] == INF):
                    queue.insert(0, (nx, ny))
                    distance[nx][ny] = distance[x][y] + 1
        return distance[gx][gy]
    return bfs()

res = -1
for yy in range(0, h):
    for xx in range(0, w):
        if dat[yy][xx] == "#":
            continue
        for yyy in range(0, h):
            for xxx in range(0, w):
                if dat[yyy][xxx] == "#":
                    continue
                step = clear_maze(yy, xx, yyy, xxx, dat)
                #print("s={0},{1} g={2},{3} cost = {4}".format(xx,yy,xxx,yyy,step))
                if step == 100000000:
                    continue
                res = max(res, step)
print(res)

Submission status: Time Limit Exceeded

Solution code:
import sys
sys.setrecursionlimit(1000000)
from collections import deque

def bfs(sx,sy,gx,gy):
    d = [[float("inf")] * w for i in range(h)]
    dx = [1, 0, -1, 0]
    dy = [0, 1, 0, -1]

    que = deque([])
    que.append((sx, sy))
    d[sx][sy] = 0

    while que:
        p = que.popleft()
        if p[0] == gx and p[1] == gy:
            break
        for i in range(4):
            nx = p[0] + dx[i]
            ny = p[1] + dy[i]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and d[nx][ny] == float("inf"):
                que.append((nx, ny))
                d[nx][ny] = d[p[0]][p[1]] + 1

    return d[gx][gy]

h,w=map(int,input().split())
s = [list(input()) for i in range(h)]
ans=0
for i in range(h):
    for j in range(w):
        if s[i][j]=='.':
            for k in range(h):
                for l in range(w):
                    if s[k][l]=='.':
                        ans = max(ans,bfs(i,j,k,l))
print(ans)