Problem:
 Score: 400 points    Problem statement  We have an H \times W grid whose squares are painted black or white. The square at the i -th row from the top and the j -th column from the left is denoted as (i, j) . Snuke would like to play the following game on this grid. At the beginning of the game, there is a character called Kenus at square (1, 1) . The player repeatedly moves Kenus up, down, left or right by one square. The game is completed when Kenus reaches square (H, W) passing only white squares. Before Snuke starts the game, he can change the color of some of the white squares to black. However, he cannot change the color of square (1, 1) and (H, W) . Also, changes of color must all be carried out before the beginning of the game. When the game is completed, Snuke's score will be the number of times he changed the color of a square before the beginning of the game. Find the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed, that is, Kenus can never reach square (H, W) regardless of how Snuke changes the color of the squares.  The color of the squares are given to you as characters s_{i, j} . If square (i, j) is initially painted by white, s_{i, j} is . ; if square (i, j) is initially painted by black, s_{i, j} is # .      Constraints   H is an integer between 2 and 50 (inclusive).  W is an integer between 2 and 50 (inclusive).  s_{i, j} is . or #  (1 \leq i \leq H, 1 \leq j \leq W) .  s_{1, 1} and s_{H, W} are . .         Input  Input is given from Standard Input in the following format:  H  W  s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}  s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}  :  :  s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}       Output  Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.        Sample Input 1 3 3
..#
#..
...      Sample Output 1 2  The score 2 can be achieved by changing the color of squares as follows:        Sample Input 2 10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................      Sample Output 2 209

Solution (Python):

from collections import deque

def bfs(maze, visited, sy, sx, gy, gx):
    queue = deque([[sy, sx]])
    visited[sy][sx] = 0
    while queue:
        y, x = queue.popleft()
        if [y, x] == [gy, gx]:
            return visited[y][x]
        for j, k in ([1, 0], [-1, 0], [0, 1], [0, -1]):
            new_y, new_x = y+j, x+k
            if 0 <= y+j <= gy and 0 <= x+k <= gx:
                if maze[new_y][new_x] == "." and \
                    visited[new_y][new_x] == -1:
                    visited[new_y][new_x] = visited[y][x] + 1
                    queue.append([new_y, new_x])

def main():
    h, w = map(int, input().split())
    S = []
    for i in range(h):
        S.append(input())
    
    visited = [[-1]*w for j in range(h)]
    res = bfs(S, visited, 0, 0, h-1, w-1)
    if res == - 1 or res == None:
        print(-1)
    else:
        counter = 0
        for i in range(h):
            for j in range(w):
                if S[i][j] == '
                    counter += 1
        print(h*w-res-1-counter)


if __name__ == '__main__':
    main()

Solution (Python):
from collections import deque


def resolve():
    h, w = map(int, input().split())
    maze = list(input() for _ in range(h))
    sy, sx = 0, 0
    gy, gx = h - 1, w - 1
    visited = [[-1 for _ in range(w)] for _ in range(h)]
    shortest = bfs(maze, visited, sy, sx, gy, gx)
    if shortest == -1:
        print(shortest)
    else:
        walls = sum([l.count("
        print(h * w - shortest - walls - 1)


def bfs(maze, visited, sy, sx, gy, gx):
    q = deque([[sy, sx]])
    visited[sy][sx] = 0
    while q:
        y, x = q.popleft()
        if y == gy and x == gx:
            return visited[gy][gx]
        for j, k in ([1, 0], [-1, 0], [0, 1], [0, -1]):
            new_y, new_x = y + j, x + k
            if new_y < 0 or new_x < 0 or new_y > gy or new_x > gx:
                continue
            if maze[new_y][new_x] == "." and visited[new_y][new_x] == -1:
                visited[new_y][new_x] = visited[y][x] + 1
                q.append([new_y, new_x])
    return -1


if __name__ == "__main__":
    resolve()

Solution (Python):
from collections import deque

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




n_blank = [flatten for inner in s for flatten in inner].count(".")

distance = [[-1]*W for _ in range(H)]
current_position = [0,0]
distance[0][0] = 0
next_positions = deque()
next_positions.append(current_position) 


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

while len(next_positions)>0 and current_position!=[H-1,W-1]:
    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)

if current_position == [H-1,W-1]:
    print(n_blank - (distance[H-1][W-1]+1))
else:
    print(-1)

Solution (Python):
h,w=map(int,input().split())
b=[["
a=0
for i in range(h):
  c=["
  for j in input():
    a+=j=="
    c.append(j)
  b.append(c+["
b+=[["
b[h][w]=0
Q=[(1,1)]
x=0
y=-1
while Q:
	x+=1
	p=[]
	for i,j in Q:
		for dx,dy in [(1,0),(-1,0),(0,1),(0,-1)]:
			if b[i+dx][j+dy]==".":
				p+=[(i+dx,j+dy)]
				b[i+dx][j+dy]="
			elif b[i+dx][j+dy]==0:
				y=x
	if y>0:break
	Q=p
if y>0:print((h*w)-a-y-1)
else:print(-1)

Solution (Python):
from collections import deque
r, c = map(int, input().split())

MAX = (r+2) * (c + 2)

sy = 0
sx = 0
gx = c-1
gy = r-1

maze = [[val for val in list(input())] for _ in range(r)]
checked_maze = [[None for _ in range(c)] for _ in range(r)]
goal = [False]

def wfs(queue):
    while len(queue) > 0:
        a = queue.popleft()
        y = a[0]
        x = a[1]
        count = a[2]
        if x < 0 or x > c-1 or y < 0 or y > r-1:
            continue
        if checked_maze[y][x]:
            continue

        if a[0] == gy and a[1] == gx:
            goal[0] = count
            break

        checked_maze[y][x] = True
        if not maze[y][x] == "
            count += 1
            queue.append((a[0]+1, a[1], count))
            queue.append((a[0]-1, a[1], count))
            queue.append((a[0], a[1]+1, count))
            queue.append((a[0], a[1]-1, count))


if __name__ == "__main__":
    que = deque()
    checked_maze[sy][sx] = 0
    que.append((sy, sx, 0))
    wfs(que)
    if not goal[0]:
        print(-1)
    else:
        masu = r * c
        blocks = 0
        for r_index in range(r):
            for c_index in range(c):
                if maze[r_index][c_index] == "
                    blocks += 1
        print(masu-goal[0]-1 -blocks)

Solution (Python):
from collections import deque


def bfs(h, w, visited, ss):
    visited[0][0] = 0
    queue = deque([])
    queue.append([0, 0])
    while queue:
        y, x = queue.popleft()
        if y == h-1 and x == w-1:
            return visited[y][x]
        for i, j in ([1, 0], [0, 1], [-1, 0], [0, -1]):
            xn, yn = x+i, y+j
            if xn < 0 or yn < 0 or xn >= w or yn >= h:
                continue
            if visited[yn][xn] == -1 and ss[yn][xn] != "
                visited[yn][xn] = visited[y][x] + 1
                queue.append([yn, xn])
    return -1


def main():
    h, w = map(int, input().split())
    ss = [input() for _ in range(h)]
    visited = [[-1 for _ in range(w)] for _ in range(h)]
    c = 0
    for s in ss:
        c += s.count("

    min_route = bfs(h, w, visited, ss)
    if min_route == -1:
        print(min_route)
    else:
        print(h*w - c - min_route - 1)


if __name__ == "__main__":
    main()

Solution (Python):
H,W = map(int, input().split())
maze = []
for i in range(H):
    maze.append(input())
    
ans = 0
for i in range(H):
    for j in range(W):
        if maze[i][j] == ".":
            ans += 1
            
Path = [[10**3 for j in range(W)] for i in range(H)]
Path[0][0] = 1
visited = [[0, 0]]

while len(visited) > 0:
    H = len(Path)
    W = len(Path[0])
    i = visited[0][0]
    j = visited[0][1]
    if i != 0:
        if Path[i-1][j] > Path[i][j]+1 and maze[i-1][j] == ".":
            Path[i-1][j] = Path[i][j]+1
            visited.append([i-1, j])
    if i != H-1:
        if Path[i+1][j] > Path[i][j]+1 and maze[i+1][j] == ".":
            Path[i+1][j] = Path[i][j]+1
            visited.append([i+1, j])
    if j != 0:
        if Path[i][j-1] > Path[i][j]+1 and maze[i][j-1] == ".":
            Path[i][j-1] = Path[i][j]+1
            visited.append([i, j-1])
    if j != W-1:
        if Path[i][j+1] > Path[i][j]+1 and maze[i][j+1] == ".":
            Path[i][j+1] = Path[i][j]+1
            visited.append([i, j+1])
    visited.pop(0)
            
if Path[-1][-1] >= 1000:
    ans = -1
else:
    ans -= Path[-1][-1]
    
print(ans)

Solution (Python):
INFTY = 1000
H,W = map(int,input().split())
S = [["
for i in range(H):
    row = list(input())
    row.insert(0,"
    row.append("
    S.append(row)
S.append(["
G = {(i,j):[] for i in range(1,H+1) for j in range(1,W+1)}
for i in range(1,H+1):
    for j in range(1,W+1):
        if S[i][j]==".":
            if S[i][j+1]==".":
                G[(i,j)].append((i,j+1))
            if S[i-1][j]==".":
                G[(i,j)].append((i-1,j))
            if S[i][j-1]==".":
                G[(i,j)].append((i,j-1))
            if S[i+1][j]==".":
                G[(i,j)].append((i+1,j))
tot = 0
for i in range(1,H+1):
    for j in range(1,W+1):
        if S[i][j]==".":
            tot += 1
dist = [[INFTY for j in range(W+2)] for i in range(H+2)]
d = [[0 for j in range(W+2)] for i in range(H+2)]
cur = (1,1)
dist[cur[0]][cur[1]] = 0
d[cur[0]][cur[1]] = 1
while True:
    for x in G[cur]:
        if d[x[0]][x[1]]==0:
            if dist[x[0]][x[1]]>dist[cur[0]][cur[1]]+1:
                dist[x[0]][x[1]] = dist[cur[0]][cur[1]]+1
    dmin = INFTY
    for i in range(1,H+1):
        for j in range(1,W+1):
            if d[i][j]==0:
                if dist[i][j]<dmin:
                    cur = (i,j)
                    dmin = dist[i][j]
    if dmin==INFTY:
        break
    else:
        d[cur[0]][cur[1]]=1
if dist[H][W]==INFTY:
    print(-1)
else:
    print(tot-2-dist[H][W]+1)

Solution (Python):
import array
import itertools
from collections import defaultdict, deque


def log(s):
    
    pass


def output(x):
    print(x, flush=True)


def input_ints():
    return map(int, input().split())


def solve():
    def find_path(p0, p1):
        queue = deque()
        footsteps = dict()

        queue.append((p0, 0))

        while queue:
            p, s = queue.popleft()
            footsteps[p] = s

            if p == p1:
                return s

            for pp in [(p[0] + 1, p[1]), (p[0] - 1, p[1]), (p[0], p[1] + 1), (p[0], p[1] - 1)]:
                if 0 <= pp[0] < width and 0 <= pp[1] < height and field[pp[1]][pp[0]] == '.' and pp not in footsteps:
                    queue.append((pp, s + 1))
                    footsteps[pp] = -1  

        return -1

    height, width = tuple(input_ints())
    field = [input() for _ in range(height)]

    s = find_path((0, 0), (width - 1, height - 1))

    if s < 0:
        return -1
    else:
        return "".join(field).count(".") - (s + 1)


def main():
    print(solve())


main()

Solution (Python):
import sys

H, W = [int(_) for _ in input().split()]
s = ["" for _ in range(H)]
for i in range(H):
    s[i] = input()
A = [[0, 0]]
d = [[] for _ in range(H)]
for i in range(0, H):
    for j in range(0, W):
        d[i].append(float('inf'))
d[0][0] = 0
while [H-1,W-1] not in A:
    
    if len(A) == 0:
        print(-1)
        sys.exit()


    res = float('inf')
    t_i = 0
    t_j = 0
    for i in range(len(A)):
        if d[A[i][0]][A[i][1]] < res:
            res = d[A[i][0]][A[i][1]]
            t_i = A[i][0]
            t_j = A[i][1]
    


    A.remove([t_i,t_j])

    if t_i - 1 >= 0 and s[t_i-1][t_j] == '.':
        if d[t_i-1][t_j] == float('inf'):
            A.append([t_i-1,t_j])
            d[t_i-1][t_j] = res + 1
        elif d[t_i-1][t_j] > res + 1:
            d[t_i-1][t_j] = res + 1



    if t_i + 1 <= H-1 and s[t_i+1][t_j] == '.':
        if d[t_i+1][t_j] == float('inf'):
            A.append([t_i+1,t_j])
            d[t_i+1][t_j] = res + 1
        elif d[t_i+1][t_j] > res + 1:
            d[t_i+1][t_j] = res + 1

   

    if t_j - 1 >= 0 and s[t_i][t_j-1] == '.':
        if d[t_i][t_j-1] == float('inf'):
            A.append([t_i,t_j-1])
            d[t_i][t_j-1] = res + 1
        elif d[t_i][t_j-1] > res + 1:
            d[t_i][t_j-1] = res + 1



    if t_j + 1 <= W-1 and s[t_i][t_j+1] == '.':
        if d[t_i][t_j+1] == float('inf'):
            A.append([t_i,t_j+1])
            d[t_i][t_j+1] = res + 1
        elif d[t_i][t_j+1] > res + 1:
            d[t_i][t_j+1] = res + 1

ans = d[H-1][W-1]

c = 0
for i in range(H):
    for j in range(W):
        if s[i][j] == '.':
            c += 1

print(c-ans-1)

Solution (Python):
from queue import Queue
h,w=map(int,input().split())
S=[list(input()) for _ in range(h)]

memo=[[-1]*w for _ in range(h)]
def bfs(q):
  x,y,cnt=q.get()
  if x<0 or x>=w or y<0 or y>=h:
    return
  elif S[y][x]=='
    return
  elif memo[y][x]<0:
    memo[y][x]=cnt
    q.put([x-1,y,cnt+1])
    q.put([x+1,y,cnt+1])
    q.put([x,y-1,cnt+1])
    q.put([x,y+1,cnt+1])

q=Queue()
q.put([0,0,0])
while not q.empty():
  bfs(q)
if memo[h-1][w-1]==-1:
  print(-1)
  exit()
cnt=0
for i in range(h):
  cnt+=S[i].count('.')
print(cnt-memo[h-1][w-1]-1)

Solution (Python):
import numpy as np
from collections import deque
H, W = map(int, input().split())
L = []

for i in range(H):
  S = input()  
  L.append(list(1 if s == "." else 0 for s in S))
L = np.array(L)
S = np.zeros((H,W))
Q = deque(())
Q.append((0,0))

while Q:
  i, j = Q.popleft()
  for ti, tj in ((i+1, j), (i, j+1), (i-1, j), (i, j-1)):
    if 0 <= ti < H and 0 <= tj < W:
      if L[ti][tj] and S[ti][tj] == 0:
        S[ti][tj] = S[i][j] + 1
        Q.append((ti, tj))
print (int(np.sum(L) - S[-1][-1] - 1) if S[-1][-1] != 0 else -1)

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

white = 0
for i in range(H):
  white += S[i].count('.')

q = [(0,0)]
S[0][0] = 0
while q:
  qq = []
  for xy in q:
    x,y = xy
    for dx,dy in ((1,0),(-1,0),(0,1),(0,-1)):
      if not(0 <= x+dx < W) or not(0 <= y+dy < H):
        continue
      elif S[y+dy][x+dx] != '.':
        continue
      S[y+dy][x+dx] = S[y][x] + 1
      qq.append((x+dx,y+dy))
  q = qq

print(white - S[-1][-1] -1 if S[-1][-1] != '.' else -1)

Solution (Python):
from collections import deque

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

cnt=0
for i in s:
    cnt+=i.count('.')

sy,sx=0,0
gy,gx=h-1,w-1

dist=[[-1]*w for i in range(h)]
dist[sy][sx]=0

que=deque()
que.append((sy,sx))

while que:
    y,x=que.popleft()

    if y==gy and x==gx:
        print(cnt-(dist[y][x]+1))
        exit()

    for dy,dx in [[1,0],[-1,0],[0,1],[0,-1]]:
        ny=y+dy
        nx=x+dx
        if 0<=ny<=h-1 and 0<=nx<=w-1 and s[ny][nx]=='.' and dist[ny][nx]==-1:
            que.append((ny,nx))
            dist[ny][nx]=dist[y][x]+1

print(-1)

Solution (Python):

def search(x, y, z):
    return [[x-1, y, z+1], [x, y-1, z+1], [x, y+1, z+1], [x+1, y, z+1]]
    
h, w = map(int, input().split())
s = [[] for _ in range(h)]
for i in range(h):
    s[i] = list(input())

sharp = 0
for i in range(h):
    for j in range(w):
        if s[i][j] == '
            sharp += 1

check = [[0] * w for _ in range(h)]
que = [[0,0,1]]
check[0][0] == 1
flag = False

while len(que) > 0:
    tmp = que.pop(0)
    
    for i in search(tmp[0], tmp[1], tmp[2]):
        if 0 <= i[0] <= h-1 and 0 <= i[1] <= w-1 and s[i[0]][i[1]] == '.':
            if check[i[0]][i[1]] == 0:
                que.append(i)
                check[i[0]][i[1]] = 1
    if tmp[0] == h-1 and tmp[1] == w-1:
        key = tmp[2]
        flag = True
        break


if check[0][0] =='
    flag = False

if flag:
    print(h*w - sharp - key)
else:
    print(-1)

Solution (Python):

from collections import deque
import sys
h,w=map(int,input().split())
field=[list(input()) for _ in range(h)]
white=0
for i in range(h):
    for j in range(w):
        if field[i][j]==".":
            white+=1
start=[0,0]
goal=[h-1,w-1]
dx=[1,0,-1,0]
dy=[0,1,0,-1]
count=0
que=deque([[[0,0]]])
field[0][0]="
while que:
    q=que.popleft()
    count+=1
    k=[]
    while q:
        p=q.pop()
        x=p[0]
        y=p[1]
        if x==h-1 and y==w-1:
            break
        for i in range(4):
            nx=x+dx[i]
            ny=y+dy[i]
            if 0<=nx and nx<h and 0<=ny and ny<w:
                if field[nx][ny]!="
                    k.append([nx,ny])
                    field[nx][ny]="
    else:
        if k:
            que.append(k)
        continue
    break
else:
    print(-1)
    sys.exit()
print(white-count)

Solution (Python):
import collections

H,W=map(int,input().split())
S=[[10**10 for j in range(W)] for i in range(H)]

Q=collections.deque([])
S[0][0]=1

s=[]
cnt=0
for i in range(H):
  s=input()
  for j in range(W):
    if s[j]=="
      S[i][j]=-1
      cnt+=1


def bfs(i,j):
  if 0<=i+1<H and S[i][j]+1<S[i+1][j] and S[i+1][j]!=-1:
    Q.append([i+1,j])
    S[i+1][j]=S[i][j]+1
  if 0<=i-1<H and S[i][j]+1<S[i-1][j] and S[i-1][j]!=-1:
    Q.append([i-1,j])
    S[i-1][j]=S[i][j]+1
  if 0<=j+1<W and S[i][j]+1<S[i][j+1] and S[i][j+1]!=-1:
    Q.append([i,j+1])
    S[i][j+1]=S[i][j]+1
  if 0<=j-1<W and S[i][j]+1<S[i][j-1] and S[i][j-1]!=-1:
    Q.append([i,j-1])
    S[i][j-1]=S[i][j]+1

Q.append([0,0])
while len(Q):
  q=Q.popleft()
  bfs(q[0],q[1])
  
  
  
print(H*W-S[-1][-1]-cnt if S[-1][-1]!=10**10 else -1)

Solution (Python):
from collections import deque

H, W = map(int, input().split())

ss = ['
ss = ['


numWhite = sum(map(lambda s: s.count('.'), ss))


dij = [(0, -1), (0, 1), (-1, 0), (1, 0)]


dist = [[float('inf')] * (W + 2) for i in range(H + 2)]

dist[1][1] = 1




Q = deque()

Q.append((1, 1))


while Q:
  
  i, j = Q.popleft()
  
  for di, dj in dij:
    
    if (ss[i + di][j + dj] == '.') & (dist[i + di][j + dj] == float('inf')):
      
      dist[i + di][j + dj] = dist[i][j] + 1
      
      Q.append((i + di, j + dj))


if dist[H][W] == float('inf'):
    print(-1)

else:
    print(numWhite - dist[H][W])

Solution (Python):
from collections import deque
h,w=map(int,input().split())
s=[list(input()) for i in range(h)]

field=[[float('inf') for i in range(w)]for j in range(h)]

q=deque()
q.append((0,0))
field[0][0]=0

n=0
while q:
    y,x=q.popleft()
    n=max(n,field[y][x])
    for dy,dx in ((1,0),(-1,0),(0,1),(0,-1)):
        ny=y+dy
        nx=x+dx
        if 0<=ny<h and 0<=nx<w and field[ny][nx]==float('inf') and s[ny][nx]!='
            q.append((ny,nx))
            field[ny][nx]=field[y][x]+1

ans=0
check=field[h-1][w-1]

shiro=0
for i in range(h):
    for j in range(w):
        if s[i][j]=='.':
            shiro+=1
ans=shiro-check-1

            
if field[h-1][w-1]!=float('inf'):
    print(ans)
else:
    print(-1)

Solution (Python):



def main():
    from collections import deque

    h, w = map(int, input().split())
    s = [list(input()) for _ in range(h)]
    dist = [[float('inf') for _ in range(w)] for _ in range(h)]
    is_visited = [[False for _ in range(w)] for _ in range(h)]
    dxy = [(1, 0), (-1, 0), (0, 1), (0, -1)]
    white_count = 0

    for i in range(h):
        for j in range(w):
            if s[i][j] == '.':
                white_count += 1

    
    
    
    d = deque()
    d.append(tuple((0, 0)))
    dist[0][0] = 1
    is_visited[0][0] = True

    while d:
        di = d.popleft()

        for dy, dx in dxy:
            nx = dx + di[1]
            ny = dy + di[0]

            if (nx < 0 or w <= nx or ny < 0 or h <= ny):
                continue
            elif s[ny][nx] == '
                continue
            elif is_visited[ny][nx]:
                continue
            else:
                dist[ny][nx] = dist[di[0]][di[1]] + 1
                is_visited[ny][nx] = True
                d.append((ny, nx))

    if dist[h - 1][w - 1] == float('inf'):
        print(-1)
    else:
        print(white_count - dist[h - 1][w - 1])


if __name__ == '__main__':
    main()

Solution (Python):
import sys
import math
from collections import defaultdict

sys.setrecursionlimit(10**7)
def input():
    return sys.stdin.readline()[:-1]

mod = 10**9 + 7

def I(): return int(input())
def II(): return map(int, input().split())
def III(): return list(map(int, input().split()))
def Line(N,num):
    if N<=0:
        for _ in range(num): return []
    elif num==1:
        return [I() for _ in range(N)]
    else:
        read_all = [tuple(II()) for _ in range(N)]
        return map(list,zip(*read_all))



H,W = II()
s = [list(map(str, input())) for _ in range(H)]

w_count = 0
for i in range(H):
    for j in range(W):
        if s[i][j] == '.':
            w_count += 1


v = (0,0)
check_visited = [[False]*W for _ in range(H)]
check_visited[v[0]][v[1]] = True
S = [v]
flag = False
c = 1
while S:
    S1 = []
    for v1 in S:
        if v1[0]==H-1 and v1[1]==W-1:
            flag = True
            break
        if v1[0]-1>=0:
            if check_visited[v1[0]-1][v1[1]] == False and s[v1[0]-1][v1[1]] == '.':
                check_visited[v1[0]-1][v1[1]] = True
                S1.append((v1[0]-1,v1[1]))
        if v1[0]+1<=H-1:
            if check_visited[v1[0]+1][v1[1]] == False and s[v1[0]+1][v1[1]] == '.':
                check_visited[v1[0]+1][v1[1]] = True
                S1.append((v1[0]+1,v1[1]))
        if v1[1]-1>=0:
            if check_visited[v1[0]][v1[1]-1] == False and s[v1[0]][v1[1]-1] == '.':
                check_visited[v1[0]][v1[1]-1] = True
                S1.append((v1[0],v1[1]-1))
        if v1[1]+1<=W-1:
            if check_visited[v1[0]][v1[1]+1] == False and s[v1[0]][v1[1]+1] == '.':
                check_visited[v1[0]][v1[1]+1] = True
                S1.append((v1[0],v1[1]+1))
    else:
        S = S1
        c += 1
        continue
    break

if flag:
    print(w_count-c)
else:
    print(-1)

Solution (Python):
from collections import deque
H,W=map(int,input().split())
wnum=0
field=[input() for _ in range(H)]
for i in range(H):
    for j in range(W):
        if field[i][j]=='.':
            wnum+=1

dist=[[-1]*W for _ in range(H)]
dist[0][0]=0
que=deque()
que.append([0,0])
while que:
    s_h,s_w=que.popleft()
    for dh,dw in [[-1,0],[1,0],[0,-1],[0,1]]:
        nh=s_h+dh
        nw=s_w+dw
        if nh<0 or nh>=H or nw<0 or nw>=W:continue
        if field[nh][nw]=='
        if dist[nh][nw]!=-1:continue
        dist[nh][nw]=dist[s_h][s_w]+1
        que.append([nh,nw])
    
if dist[H-1][W-1]==-1:
    print(-1)
else:
    print(wnum-dist[H-1][W-1]-1)

Solution (Python):
from collections import deque
H,W=map(int,input().split())
wnum=0
field=[input() for _ in range(H)]
for i in range(H):
    for j in range(W):
        if field[i][j]=='.':
            wnum+=1

dist=[[-1]*W for _ in range(H)]
dist[0][0]=0
que=deque()
que.append([0,0])
while (len(que)!=0):
    s_h,s_w=que.popleft()
    for dh,dw in [[-1,0],[1,0],[0,-1],[0,1]]:
        nh=s_h+dh
        nw=s_w+dw
        if nh<0 or nh>=H or nw<0 or nw>=W:continue
        if field[nh][nw]=='
        if dist[nh][nw]!=-1:continue
        dist[nh][nw]=dist[s_h][s_w]+1
        que.append([nh,nw])
if dist[H-1][W-1]==-1:
    print(-1)
else:
    print(wnum-(dist[H-1][W-1]+1))

Solution (Python):
from collections import deque

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

queue = deque([[0,0]])
visited = [[-1 for i in range(w)]for j in range(h)]
visited[0][0] = 1
while queue:
    x,y = queue.popleft()
    if x!=0:
        if S[x-1][y] == '.' and visited[x-1][y] == -1:
            queue.append([x-1,y])
            visited[x-1][y] = visited[x][y] + 1
    if x!=h-1:
        if S[x+1][y] == '.' and visited[x+1][y] == -1:
            queue.append([x+1,y])
            visited[x+1][y] = visited[x][y] + 1
    if y!=0:
        if S[x][y-1] == '.' and visited[x][y-1] == -1:
            queue.append([x,y-1])
            visited[x][y-1] = visited[x][y] + 1
    if y!=w-1:
        if S[x][y+1] == '.' and visited[x][y+1] == -1:
            queue.append([x,y+1])
            visited[x][y+1] = visited[x][y] + 1

dots = 0
for i in range(h):
    for j in range(w):
        if S[i][j] == '.':
            dots += 1

if visited[h-1][w-1] != -1:
    print(dots-visited[h-1][w-1])
else:
    print(-1)

Solution (Python):
from collections import deque
h,w= map(int,input().split())
dist = [[-1 for _ in range(w)]for _ in range(h)]
y = [1,-1, 0, 0]
x = [0, 0, 1,-1]
graph = []
q = deque([(0,0)])
count = -2
for i in range(h):
    j = input()
    count += j.count(".")
    graph.append(j)
while q:
    v = q.popleft()
    for j in range(4):
        nh,nw = v[0]+y[j],v[1]+x[j]
        if nh < 0 or nh >= h or nw < 0 or nw >= w or graph[nh][nw] == "
        if nh == h-1 and nw == w-1:
            dist[nh][nw] = dist[v[0]][v[1]]+1
            break
        else:
            q.append((nh,nw))
            dist[nh][nw] = dist[v[0]][v[1]]+1
    else:continue
    break
else:print(-1);exit()
print(count-dist[h-1][w-1])

Solution (Python):
import sys
input=sys.stdin.readline
import collections

H,W = map(int, input().split())

maze = [] 
for _ in range(H):
    maze.append(input().strip())
move = {(1,0), (0,1), (-1,0), (0,-1)} 

Inf = 10**9
def bfs():
    d = [[Inf]*W for _ in range(H)] 
    d[0][0] = 0

    q = collections.deque()
    q.append((0,0))
    while q:
        p = q.popleft() 
        if p == (H-1, W-1):
            break 
        for dh, dw in move:
            nh, nw = p[0] + dh, p[1] + dw 
            if 0 <= nw and nw < W and 0 <= nh and nh < H: 
                if maze[nh][nw] == "." and d[nh][nw] == Inf: 
                    d[nh][nw] = d[p[0]][p[1]] + 1 
                    q.append((nh, nw)) 
    return d[H-1][W-1]

def main():
    d = bfs()
    if d == Inf:
        print(-1)
    else:
        x = 0
        for s in maze:
            x += s.count("
        print(W*H - x - (d+1))
    
if __name__ == '__main__':
    main()

Solution (Python):
from collections import defaultdict
from collections import deque
h,w=map(int,input().split())
s=[list(input()) for i in range(h)]
field=[[float('inf') for i in range(w)] for j in range(h)]

q=deque()
q.append((0,0))
field[0][0]=0

dx=[0,1,0,-1]
dy=[1,0,-1,0]

while q:
    y,x=q.popleft()
    
    for i in range(4):
        nx=x+dx[i]
        ny=y+dy[i]
        if 0<=nx<w and 0<=ny<h and field[ny][nx]==float('inf') and s[ny][nx]!='
            field[ny][nx]=field[y][x]+1
            q.append((ny,nx))
check=field[h-1][w-1]

shiro=0
for i in range(h):
    for j in range(w):
        if s[i][j]=='.':
            shiro+=1
ans=shiro-check-1

print(ans if check!=float('inf') else -1)

Solution (Python):
from collections import defaultdict
from collections import deque
h,w=map(int,input().split())
s=[list(input()) for i in range(h)]
field=[[float('inf') for i in range(w)] for j in range(h)]

q=deque()
q.append((0,0))
field[0][0]=0

dx=[0,1,0,-1]
dy=[1,0,-1,0]

while q:
    y,x=q.popleft()
    
    for i in range(4):
        nx=x+dx[i]
        ny=y+dy[i]
        if 0<=nx<w and 0<=ny<h and field[ny][nx]==float('inf') and s[ny][nx]!='
            field[ny][nx]=field[y][x]+1
            q.append((ny,nx))
check=field[h-1][w-1]

dic=defaultdict(int)
for i in range(h):
    for j in range(w):
        dic[field[i][j]]+=1
ans=0

for key,value in dic.items():
    if key!=float('inf') and key <=check:
        ans+=value-1
    elif key!=float('inf') and key >check:
        ans+=value
    

for i in range(h):
    for j in range(w):
        if field[i][j]==float('inf') and s[i][j]=='.':
            ans+=1
print(ans if check!=float('inf') else -1)

Solution (Python):
H,W=map(int, input().split())
S = tuple(input().rstrip() for _ in range(H))
a=0
d=[(1,0),(-1,0),(0,1),(0,-1)]
lity=[[0 for i in range(W)] for j in range(H)]
lity[0][0]=1
def roop()->None:
  p=[(0,0)]
  while p:
    x,y=p.pop(0)
    for dx,dy in d:
      if 0<=x+dx<H and 0<=y+dy<W and S[x+dx][y+dy]=='.' and lity[x+dx][y+dy]==0:
        p.append((x+dx,y+dy))
        lity[x+dx][y+dy]=lity[x][y]+1
roop()
white=sum(t.count(".") for t in S)
x=lity[-1][-1]
ans = white - x
if 0<x:
  print(ans)
else:
  print(-1)

Solution (Python):
from collections import deque
_in = list(open(0))
h, w = list(map(int, _in[0].split()))

a = [[False]*(w+2)]
for y in _in[1:]:
    a.append([False] + [x!='
a.append([False]*(w+2))

ans = 0
for x in a:
    ans += sum(x)

s = deque()
s.append((1,1))

while s:
    ns = deque()
    for i, j in s:
        if i==h and j==w:
            ns = deque()
            break
        if a[i-1][j]:
            a[i-1][j] = False
            ns.append((i-1, j))
        if a[i+1][j]:
            a[i+1][j] = False
            ns.append((i+1, j))
        if a[i][j-1]:
            a[i][j-1] = False
            ns.append((i, j-1))
        if a[i][j+1]:
            a[i][j+1] = False
            ns.append((i, j+1))
        
    s = ns
    ans -= 1

if i==h and j==w:
    print(ans)
else:
    print(-1)

Solution (Python):
H,W=map(int, input().split())
S = tuple(input().rstrip() for _ in range(H))
a=0
d=[(1,0),(-1,0),(0,1),(0,-1)]
lity=[[0 for i in range(W)] for j in range(H)]
lity[0][0]=1
def roop()->None:
  p=[(0,0)]
  while p:
    x,y=p.pop(0)
    for dx,dy in d:
      if 0<=x+dx<H and 0<=y+dy<W and S[x+dx][y+dy]=='.' and lity[x+dx][y+dy]==0:
        p.append((x+dx,y+dy))
        lity[x+dx][y+dy]=lity[x][y]+1
roop()
white=sum(t.count(".") for t in S)
x=lity[-1][-1]
ans = white - x if x else -1
print(ans)

Solution (Python):
H, W = map(int, input().split())
l = [list(input()) for _ in range(H)]

from collections import deque
q = deque([(0, 0)])
d = [(1, 0), (-1, 0), (0, 1), (0, -1)]
l[0][0] = 0

while q:
    y, x = q.popleft()
    for dy, dx in d:
        if 0 <= y+dy < H and 0 <= x+dx < W and l[y+dy][x+dx] == '.':
            l[y+dy][x+dx] = l[y][x] + 1
            q.append((y+dy, x+dx))

try:
    g = l[H-1][W-1]
    total = 0
    for _l in l:
        for i in _l:
            if i != '
                total += 1
    print(total - g - 1)
except:
    print(-1)