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 collections import deque
import math,itertools,fractions,heapq,bisect,sys,copy

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[list(S()) for _ in range(h)]

  ans=0
  visited=[[-1 for __ in range(w)] for _ in range(h)]
  q=deque()
  for i in range(h):
    for j in range(w):
      if field[i][j]=='#':
        continue
      q.append((i,j,0))
      for _i in range(h):
        for _j in range(w):
          visited[_i][_j]=-1
      while len(q)>0:
        y,x,c=q.popleft()
        visited[y][x]=c

        for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
          ny=y+dy
          nx=x+dx
          if 0<=ny<h and 0<=nx<w:
            if field[ny][nx]=='#':
              continue
            if visited[ny][nx]!=-1:
              continue
            q.append((ny,nx,c+1))
      ans=max(ans,c)
  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[list(S()) for _ in range(h)]

  ans=0
  visited=[[-1 for __ in range(w)] for _ in range(h)]
  q=collections.deque()
  for i in range(h):
    for j in range(w):
      if field[i][j]=='#':
        continue
      q.append((i,j,0))
      for _i in range(h):
        for _j in range(w):
          visited[_i][_j]=-1
      while len(q)>0:
        y,x,c=q.popleft()
        visited[y][x]=c

        for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
          ny=y+dy
          nx=x+dx
          if 0<=ny<h and 0<=nx<w:
            if field[ny][nx]=='#':
              continue
            if visited[ny][nx]!=-1:
              continue
            q.append((ny,nx,c+1))
      ans=max(ans,c)
  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0
  visited=[[-1 for __ in range(w)] for _ in range(h)]
  q=collections.deque()
  for i in range(h):
    for j in range(w):
      if field[i][j]=='#':
        continue
      q.append((i,j,0))
      for _i in range(h):
        for _j in range(w):
          visited[_i][_j]=-1
      while len(q)>0:
        y,x,c=q.popleft()
        visited[y][x]=c

        for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
          ny=y+dy
          nx=x+dx
          if 0<=ny<h and 0<=nx<w:
            if field[ny][nx]=='#':
              continue
            if visited[ny][nx]!=-1:
              continue
            q.append((ny,nx,c+1))
      ans=max(ans,c)
  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0
  visited=[[-1 for __ in range(w)] for _ in range(h)]
  q=collections.deque()
  for i in range(h):
    for j in range(w):
      if field[i][j]=='#':
        continue
      q.append((i,j,0))
      for _i in range(h):
        for _j in range(w):
          visited[_i][_j]=-1
      while len(q)>0:
        y,x,c=q.popleft()
        visited[y][x]=c

        for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
          ny=y+dy
          nx=x+dx
          if 0<=ny<h and 0<=nx<w:
            if field[ny][nx]=='#':
              continue
            if visited[ny][nx]!=-1:
              continue
            _ans=c+1
            q.append((ny,nx,c+1))
      ans=max(ans,_ans)
  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0
  visited=[[-1 for __ in range(w)] for _ in range(h)]
  q=collections.deque()
  for i in range(h):
    for j in range(w):
      if field[i][j]=='#':
        continue
      q.append((i,j,0))
      for _i in range(h):
        for _j in range(w):
          visited[_i][_j]=-1
      while len(q)>0:
        y,x,c=q.popleft()
        visited[y][x]=c

        for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
          ny=y+dy
          nx=x+dx
          if 0<=ny<h and 0<=nx<w:
            if field[ny][nx]=='#':
              continue
            if visited[ny][nx]!=-1:
              continue
            ans=max(ans,c+1)
            q.append((ny,nx,c+1))

  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0
  visited=[[-1 for __ in range(w)] for _ in range(h)]
  ans=0
  for i in range(h):
    for j in range(w):
      q=collections.deque()
      if field[i][j]=='#':
        continue
      q.append((i,j,0))
      for _i in range(h):
        for _j in range(w):
          visited[_i][_j]=-1
      while len(q)>0:
        y,x,c=q.popleft()
        visited[y][x]=c

        for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
          ny=y+dy
          nx=x+dx
          if 0<=ny<h and 0<=nx<w:
            if field[ny][nx]=='#':
              continue
            if visited[ny][nx]!=-1:
              continue
            ans=max(ans,c+1)
            q.append((ny,nx,c+1))

  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0
  visited=[[-1 for __ in range(w)] for _ in range(h)]
  for i in range(h):
    for j in range(w):
      for k in range(h):
        for l in range(w):
          q=collections.deque()
          if field[i][j]=='#' or field[k][l]=='#':
            continue
          q.append((k,l,0))
          for _i in range(h):
            for _j in range(w):
              visited[_i][_j]=-1
          while len(q)>0:
            y,x,c=q.popleft()
            visited[y][x]=c
            if y==i and x==j:
              ans=max(ans,c)
              break

            for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
              ny=y+dy
              nx=x+dx
              if 0<=ny<h and 0<=nx<w:
                if field[ny][nx]=='#':
                  continue
                if visited[ny][nx]!=-1:
                  continue
                q.append((ny,nx,c+1))

  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0

  for i in range(h):
    for j in range(w):
      for k in range(h):
        for l in range(w):
          q=collections.deque()
          if field[i][j]=='#' or field[k][l]=='#':
            continue
          q.append((k,l,0))
          visited=[[-1 for __ in range(w)] for _ in range(h)]
          while len(q)>0:
            y,x,c=q.popleft()
            visited[y][x]=c
            if y==i and x==j:
              ans=max(ans,c)
              break

            for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
              ny=y+dy
              nx=x+dx
              if 0<=ny<h and 0<=nx<w:
                if field[ny][nx]=='#':
                  continue
                if visited[ny][nx]!=-1:
                  continue
                q.append((ny,nx,c+1))

  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0

  for i in range(h):
    for j in range(w):
      for k in range(h):
        for l in range(w):
          q=collections.deque()
          if field[i][j]=='#' or field[k][l]=='#':
            continue
          q.append((k,l,0))
          visited=[[-1]*w for _ in range(h)]
          for _ in range(inf):
            if len(q)<=0:
              break
            y,x,c=q.popleft()
            visited[y][x]=c
            if y==i and x==j:
              ans=max(ans,c)
              break

            for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
              ny=y+dy
              nx=x+dx
              if 0<=ny<h and 0<=nx<w:
                if field[ny][nx]=='#':
                  continue
                if visited[ny][nx]!=-1:
                  continue
                q.append((ny,nx,c+1))

  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0

  for i in range(h):
    for j in range(w):
      for k in range(h):
        for l in range(w):
          q=collections.deque()
          if field[i][j]=='#' or field[k][l]=='#':
            continue
          q.append((k,l,0))
          visited=[[-1]*w for _ in range(h)]
          while len(q)>0:
            y,x,c=q.popleft()
            if visited[y][x]!=-1:
              continue
            visited[y][x]=c
            if y==i and x==j:
              ans=max(ans,c)
              break

            for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
              ny=y+dy
              nx=x+dx
              if 0<=ny<h and 0<=nx<w:
                if field[ny][nx]=='#':
                  continue
                if visited[ny][nx]!=-1:
                  continue
                q.append((ny,nx,c+1))

  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0

  for i in range(h):
    for j in range(w):
      for k in range(h):
        for l in range(w):
          q=collections.deque()
          if field[i][j]=='#' or field[k][l]=='#':
            continue
          q.append((k,l,0))
          visited=[[-1]*w for _ in range(h)]
          while len(q)>0:
            y,x,c=q.popleft()
            visited[y][x]=c
            if y==i and x==j:
              ans=max(ans,c)
              break

            for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
              ny=y+dy
              nx=x+dx
              if 0<=ny<h and 0<=nx<w:
                if field[ny][nx]=='#':
                  continue
                if visited[ny][nx]!=-1:
                  continue
                q.append((ny,nx,c+1))

  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0

  for i in range(h):
    for j in range(w):
      for k in range(h):
        for l in range(w):
          q=collections.deque()
          if field[i][j]=='#' or field[k][l]=='#':
            continue
          q.append((k,l,0))
          visited=[[-1]*w for _ in range(h)]
          while len(q)>0:
            y,x,c=q.popleft()
            visited[y][x]=c
            if y==i and x==j:
              ans=max(ans,c)
              break

            for dy,dx in ((-1,0),(0,1),(1,0),(0,-1)):
              ny=y+dy
              nx=x+dx
              if 0<=ny and 0<=nx and ny<h and nx<w:
                if field[ny][nx]=='#':
                  continue
                if visited[ny][nx]!=-1:
                  continue
                q.append((ny,nx,c+1))

  return ans

# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import math,itertools,fractions,heapq,bisect,sys,copy,collections

sys.setrecursionlimit(10**7)
inf=10**20
mod=10**9+7
dd=[(-1,0),(0,1),(1,0),(0,-1)]
ddn=[(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return input()

def main():
  h,w=LI()
  field=[S() for _ in range(h)]

  ans=0

  for i in range(h):
    for j in range(w):
      for k in range(h):
        for l in range(w):
          q=collections.deque()
          if field[i][j]=='#' or field[k][l]=='#':
            continue
          q.append((k,l,0))
          visited=[[-1]*w for _ in range(h)]
          while len(q)>0:
            y,x,c=q.popleft()
            visited[y][x]=c
            if y==i and x==j:
              ans=max(ans,c)
              # print(ans,i,j,k,l)
              break

            for dy,dx in dd:
              ny=y+dy
              nx=x+dx
              if 0<=ny and 0<=nx and ny<h and nx<w:
                if field[ny][nx]=='#':
                  continue
                if visited[ny][nx]!=-1:
                  continue
                q.append((ny,nx,c+1))

  return ans


# main()
print(main())

Submission status: Time Limit Exceeded

Solution code:
import numpy as np
from collections import deque

H, W = map(int, input().split())
maze = np.array([input() for _ in range(H)])


def bfs(sty, stx):
    visited = np.array([[-1]*W for _ in range(H)])
    q = deque()
    q.append((sty, stx, 0))


    def is_ok(y, x):
        if not 0 <= y <= H - 1:
            return False
        if not 0 <= x <= W - 1:
            return False
        if visited[y][x] != -1:
            return False
        if maze[y][x] == '#':
            return False
        return True


    while q:
        y, x, lv = q.popleft()
        visited[y][x] = lv
        for i in (-1, 1):
            if is_ok(y+i, x):
                q.append((y+i, x, lv+1))
            if is_ok(y, x+i):
                q.append((y, x+i, lv+1))

    return np.max(visited)

res = 0
for i in range(H):
    for j in range(W):
        if maze[i][j] == '.':
            steps = bfs(i, j)
            if steps > res:
                res = steps

print(res)

Submission status: Time Limit Exceeded

Solution code:
import numpy as np
from collections import deque

H, W = map(int, input().split())
maze = np.array([input() for _ in range(H)])


def bfs(sty, stx):
    visited = np.array([[-1 for _ in range(W)] for _ in range(H)])
    q = deque()
    q.append((sty, stx, 0))


    def is_ok(y, x):
        if not 0 <= y <= H - 1:
            return False
        if not 0 <= x <= W - 1:
            return False
        if visited[y][x] != -1:
            return False
        if maze[y][x] == '#':
            return False
        return True


    while q:
        y, x, lv = q.popleft()
        visited[y][x] = lv
        for i in (-1, 1):
            if is_ok(y+i, x):
                q.append((y+i, x, lv+1))
            if is_ok(y, x+i):
                q.append((y, x+i, lv+1))

    return np.max(visited)

res = 0
for i in range(H):
    for j in range(W):
        if maze[i][j] == '.':
            steps = bfs(i, j)
            if steps > res:
                res = steps

print(res)

Submission status: Time Limit Exceeded

Solution code:
import numpy as np
from collections import deque

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


def bfs(sty, stx):
    visited = [[-1 for _ in range(W)] for _ in range(H)]
    q = deque()
    q.append([sty, stx, 0])


    def is_ok(y, x):
        if not 0 <= y <= H - 1:
            return False
        if not 0 <= x <= W - 1:
            return False
        if visited[y][x] != -1:
            return False
        if maze[y][x] == '#':
            return False
        return True


    while q:
        y, x, lv = q.popleft()
        visited[y][x] = lv
        for i in (-1, 1):
            if is_ok(y+i, x):
                q.append([y+i, x, lv+1])
            if is_ok(y, x+i):
                q.append([y, x+i, lv+1])

    visited = np.array(visited)
    return np.max(visited)

res = 0
for i in range(H):
    for j in range(W):
        if maze[i][j] == '.':
            steps = bfs(i, j)
            if steps > res:
                res = steps

print(res)

Submission status: Time Limit Exceeded

Solution code:
import sys
import socket
import numpy
from itertools import product

hostnames = ['N551J', 'F551C', 'X553M']
input_file = 'd2.in'
if socket.gethostname() in hostnames:
    sys.stdin = open(input_file)


def read_int_list():
    return list(map(int, input().split()))


def read_int():
    return int(input())


def read_str_list():
    return input().split()


def read_str():
    return input()


def solve():
    h, w = read_int_list()
    a = [read_str() for _ in range(h)]
    dx = [-1, 1, 0, 0]
    dy = [0, 0, -1, 1]
    inf = 10 ** 3
    d = numpy.full(shape=(h, w, h, w), fill_value=inf, 
            dtype=numpy.int16)
    for i, j in product(range(h), range(w)):
        d[i][j][i][j] = 0

    for i, j in product(range(h), range(w)):
        if a[i][j] == '#':
            continue
        for di, dj in zip(dx, dy):
            k = i + di
            l = j + dj
            if not (0 <= k < h and 0 <= l < w):
                continue
            if a[k][l] == '#':
                continue
            d[i][j][k][l] = 1

    for k, kk in product(range(h), range(w)):
        for i, ii in product(range(h), range(w)):
            for j, jj in product(range(h), range(w)):
                if d[i][ii][j][jj] > d[i][ii][k][kk] + d[k][kk][j][jj]:
                    d[i][ii][j][jj] = d[i][ii][k][kk] + d[k][kk][j][jj]


    res = 0
    for i, ii in product(range(h), range(w)):
        for j, jj in product(range(h), range(w)):
            if d[i][ii][j][jj] == inf:
                continue
            if res < d[i][ii][j][jj]:
                res = d[i][ii][j][jj]
    return res


def main():
    res = solve()
    print(res)


if __name__ == '__main__':
    main()

Submission status: Time Limit Exceeded

Solution code:
import sys
import socket
import numpy
from itertools import product

hostnames = ['N551J', 'F551C', 'X553M']
input_file = 'd2.in'
if socket.gethostname() in hostnames:
    sys.stdin = open(input_file)


def read_int_list():
    return list(map(int, input().split()))


def read_int():
    return int(input())


def read_str_list():
    return input().split()


def read_str():
    return input()


def solve():
    h, w = read_int_list()
    a = [read_str() for _ in range(h)]
    dx = [-1, 1, 0, 0]
    dy = [0, 0, -1, 1]
    inf = 10 ** 3
    d = numpy.full(shape=(h, w, h, w), fill_value=inf)
    for i, j in product(range(h), range(w)):
        d[i][j][i][j] = 0

    for i, j in product(range(h), range(w)):
        if a[i][j] == '#':
            continue
        for di, dj in zip(dx, dy):
            k = i + di
            l = j + dj
            if not (0 <= k < h and 0 <= l < w):
                continue
            if a[k][l] == '#':
                continue
            d[i][j][k][l] = 1

    for k, kk in product(range(h), range(w)):
        for i, ii in product(range(h), range(w)):
            for j, jj in product(range(h), range(w)):
                if d[i][ii][j][jj] > d[i][ii][k][kk] + d[k][kk][j][jj]:
                    d[i][ii][j][jj] = d[i][ii][k][kk] + d[k][kk][j][jj]


    res = 0
    for i, ii in product(range(h), range(w)):
        for j, jj in product(range(h), range(w)):
            if d[i][ii][j][jj] == inf:
                continue
            if res < d[i][ii][j][jj]:
                res = d[i][ii][j][jj]
    return int(res)


def main():
    res = solve()
    print(res)


if __name__ == '__main__':
    main()

Submission status: Time Limit Exceeded

Solution code:
import numpy as np


HEIGHT, WIDTH = map(int, input().split())
S = [input() for _ in range(HEIGHT)]
M = np.array([[0 if char == "." else -1 for char in row] for row in S], dtype=np.int64)


def bfs(i, j):
    for v in np.array([[1, 0], [0, 1]]):
        for flag in [1, -1]:
            di, dj = v * flag
            new_i, new_j = i + di, j + dj
            if (
                0 <= new_i < HEIGHT
                and 0 <= new_j < WIDTH
                and (new_i, new_j) != START
                and MM[new_i, new_j] == 0
            ):
                MM[new_i, new_j] = MM[i, j] + 1
                STACK.append((new_i, new_j))


ANS = 0
for i in range(HEIGHT):
    for j in range(WIDTH):
        if M[i, j] == 0:
            MM = M.ravel().copy().reshape(HEIGHT, WIDTH)
            START = (i, j)
            STACK = [START]
            while STACK:
                bfs(*STACK.pop(0))
            ANS = max(ANS, MM.max())
print(ANS)

Submission status: Time Limit Exceeded

Solution code:
H, W = [int(i) for i in input().split()]
SSS = [["#" for i in range(W+2)]]
for i in range(H):
    buff = "#"+input()+"#"
    SSS.append([i for i in buff])
SSS.append(["#" for i in range(W+2)])

def maxlen(a,b):
    willgo = [[a,b]]
    finish =[]
    dist = [[-1 for i in range(W+2)] for j in range(H+2)]
    dist[a][b]=0

    while len(willgo) >=1:
        now = willgo.pop(0) #探索候補リストから優先度の高い先頭要素を取ってくる
        finish.append(now) #今いる場所を訪問済みに追加
        nextplace = [] #次に行ける所を探す
        nowh = now[0]
        noww = now[1]

        if SSS[nowh-1][noww] == ".":
            nextplace.append([nowh-1,noww])
        if SSS[nowh+1][noww] == ".":
            nextplace.append([nowh+1,noww])
        if SSS[nowh][noww-1] == ".":
            nextplace.append([nowh,noww-1])
        if SSS[nowh][noww+1] == ".":
            nextplace.append([nowh,noww+1])
        
        for n in nextplace:
            if n in finish: continue
            if n in willgo: continue
            willgo.append(n)
            dist[n[0]][n[1]]=dist[nowh][noww]+1

    return max([max(j) for j in dist])




ans = 0
for i in range(1,H+1):
    for j in range(1,W+1):
        if SSS[i][j]==".":
            ans = max(ans,maxlen(i,j))
print(ans)

Submission status: Time Limit Exceeded

Solution code:
H, W = [int(i) for i in input().split()]
SSS = [["#" for i in range(W+2)]]
for i in range(H):
    buff = "#"+input()+"#"
    SSS.append([i for i in buff])
SSS.append(["#" for i in range(W+2)])

def maxlen(a,b):
    willgo = [[a,b,0]]
    finish =[]

    while len(willgo) >=1:
        now = willgo.pop(0) #探索候補リストから優先度の高い先頭要素を取ってくる
        finish.append(now) #今いる場所を訪問済みに追加

        nextplace = [] #次に行ける所を探す
        nowh = now[0]
        noww = now[1]
        width = now[2]
        if SSS[nowh-1][noww] == ".":
            nextplace.append([nowh-1,noww,width+1])
        if SSS[nowh+1][noww] == ".":
            nextplace.append([nowh+1,noww,width+1])
        if SSS[nowh][noww-1] == ".":
            nextplace.append([nowh,noww-1,width+1])
        if SSS[nowh][noww+1] == ".":
            nextplace.append([nowh,noww+1,width+1])
        
        for i in nextplace:
            if [i[0],i[1]] in [[f[0],f[1]] for f in finish]: continue
            if [i[0],i[1]] in [[w[0],w[1]] for w in willgo]: continue
            willgo.append(i)

    return finish[-1][2]

ans = 0
for i in range(1,H+1):
    for j in range(1,W+1):
        if SSS[i][j]==".":
            ans = max(ans,maxlen(i,j))
print(ans)

Submission status: Time Limit Exceeded

Solution code:
from collections import deque

h,w = map(int,input().split())
maze = []
ans = 0
dy_dx = [[0,1],[1,0],[0,-1],[-1,0]]
for i in range(h):
    maze.append(input())
for i in range(h):
    for j in range(w):
        if maze[i][j] == '.':
            ne = deque([[i,j]])
            dist = [[0]*w for k in range(h)]
            checked = [[0]*w for k in range(h)]
            while len(ne) != 0:
                cur = ne.popleft()
                checked[cur[0]][cur[1]] = 1
                for l in range(4):
                    t = cur[0]+dy_dx[l][0]
                    u = cur[1]+dy_dx[l][1]
                    if (0 <= t <= h-1) and (0 <= u <= w-1):
                        if checked[t][u] == 0:
                            if maze[t][u] == '.':
                                dist[t][u] = dist[cur[0]][cur[1]]+1
                                ne.append([t,u])
                                ans = max(ans,dist[t][u])
print(ans)

Submission status: Time Limit Exceeded

Solution code:
import collections

h,w = map(int,input().split())
maze = []
ans = 0
dy_dx = [[0,1],[1,0],[0,-1],[-1,0]]
for i in range(h):
    maze.append(input())
for i in range(h):
    for j in range(w):
        if maze[i][j] == '.':
            ne = collections.deque()
            dist = [[0]*w for k in range(h)]
            checked = [[0]*w for k in range(h)]
            ne.append([i,j])
            while len(ne) != 0:
                cur = ne.popleft()
                checked[cur[0]][cur[1]] = 1
                for l in range(4):
                    t = cur[0]+dy_dx[l][0]
                    u = cur[1]+dy_dx[l][1]
                    if (0 <= t <= h-1) and (0 <= u <= w-1):
                        if checked[t][u] == 0:
                            if maze[t][u] == '.':
                                dist[t][u] = dist[cur[0]][cur[1]]+1
                                ne.append([t,u])
                                ans = max(ans,dist[t][u])
print(ans)

Submission status: Time Limit Exceeded

Solution code:
import collections

h,w = map(int,input().split())
maze = []
ans = 0
dy_dx = [[0,1],[1,0],[0,-1],[-1,0]]
for i in range(h):
    maze.append(input())
for i in range(h):
    for j in range(w):
        if maze[i][j] == '.':
            next = collections.deque()
            dist = []
            checked = []
            curmax = 0
            for k in range(h):
                a = [0]*w
                b = [0]*w
                dist.append(a)
                checked.append(b)
            next.append([i,j])
            while len(next) != 0:
                cur = next.popleft()
                checked[cur[0]][cur[1]] = 1
                for l in range(4):
                    t = cur[0]+dy_dx[l][0]
                    u = cur[1]+dy_dx[l][1]
                    if (0 <= t <= h-1) and (0 <= u <= w-1):
                        if checked[t][u] == 0:
                            if maze[t][u] == '.':
                                dist[t][u] = dist[cur[0]][cur[1]]+1
                                next.append([t,u])
                                curmax = max(curmax,dist[t][u])
            ans = max(ans,curmax)
print(ans)