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):
def bfs(S,H,W):
    stk = [(0,0)]
    cnt = 0
    seen = set()
    while True:
        nxt = []
        while stk:
            h,w = stk.pop()
            if(not (0<=h<H and 0<=w<W) or S[h][w]=='
                continue
            elif(h==H-1 and w==W-1):
                break
            seen.add((h,w))
            li=[(1,0),(-1,0),(0,-1),(0,1)]
            for x,y in li:
                nxt.append((h+y,w+x))
        else:
            stk = nxt
            cnt += 1
            if(cnt>H*W+5):return -1
            continue
        break
    return cnt

H,W = [int(x) for x in input().split()]
S = [list(input()) for _ in range(H)]
wht = 0
for s in S:
    wht += s.count('.')
rt = bfs(S,H,W)
if(rt>=0):
    print(wht-(rt+1))
else:
    print(rt)

Solution (Python):
from collections import Counter
def main():
    H,W = map(int,input().split())
    s = [list(map(str,input())) for _ in range(H)]
    INF = 10**5
    maze_list = [[INF for _ in range(W)] for _ in range(H)]
    maze_list[0][0] = 0
    def item(array):
        return [item for sublist in array for item in sublist]

    counter = list(Counter(item(s)).items())
    num = 0
    for i in range(len(counter)):
        if counter[i][0] == ".":
            num = counter[i][1]
            break

    queue = []
    queue.insert(0,(0,0))
    while len(queue):
        x,y = queue.pop()
        if x == H-1 and y == W-1:
            break
        for i in range(4):
            nx,ny = x + [1,0,-1,0][i],y + [0,1,0,-1][i]
            if (0<=nx and nx<H and 0<=ny and ny<W and \
                s[nx][ny]!="
                queue.insert(0,(nx,ny))
                maze_list[nx][ny] = maze_list[x][y] + 1

    if maze_list[H-1][W-1] == INF:
        print(-1)
    else:
        print(num-maze_list[H-1][W-1]-1)

if __name__ == "__main__":
    main()

Solution (Python):
from collections import deque

H, W = map(int, input().split())
grid = [list(input()) for _ in range(H)]
cnt = 0
INF = 10**4
dp = [[INF] * (W) for _ in range(H)]
dp[0][0] = 0
for i in range(H):
  for j in range(W):
    if grid[i][j] == '.':
      cnt += 1
dy = [1,0,-1,0]
dx = [0,1,0,-1]
que = deque([])
que.append((0, 0))
while len(que) > 0:
  cy, cx = que.popleft()
  if cy == H-1 and cx == W-1:
    break
  for i in range(4):
    ny, nx = cy+dy[i], cx+dx[i]
    if ny >= 0 and ny <= H-1 and nx >= 0 and nx <= W-1:
      if dp[ny][nx] == INF and grid[ny][nx] == '.':
        dp[ny][nx] = dp[cy][cx] + 1
        que.append((ny, nx))
if dp[H-1][W-1] == INF:
  print(-1)
else:
  print(cnt-dp[H-1][W-1]-1)

Solution (Python):
import queue
H, W = map(int, input().split())
numw = 0
S = []
for i in range(H):
  ss = input()
  numw += ss.count(".")
  S.append(ss)

D = [[-1]*W for i in range(H)]
q = queue.Queue()
q.put((0, 0, 0))
D[0][0] = 0
while not(q.empty()):
  i, j, d = q.get()
  if j > 0 and S[i][j-1] == "." and D[i][j-1] < 0:
    D[i][j-1] = d+1
    q.put((i, j-1, d+1))
  if i > 0 and S[i-1][j] == "." and D[i-1][j] < 0:
    D[i-1][j] = d+1
    q.put((i-1, j, d+1))
  if j+1 < W and S[i][j+1] == "." and D[i][j+1] < 0:
    D[i][j+1] = d+1
    q.put((i, j+1, d+1))
  if i+1 < H and S[i+1][j] == "." and D[i+1][j] < 0:
    D[i+1][j] = d+1
    q.put((i+1, j, d+1))

if D[H-1][W-1] < 0:
  print(-1)
  exit()
r = numw-D[H-1][W-1]-1
print(r)

Solution (Python):
import sys
sys.setrecursionlimit(1000000000)
from collections import deque
def bfs(Y,X,count):
    
    
    reached[Y][X]=True

    if Y==goalY and X==goalX:
        result=0
        for i in range(H):
            for j in range(W):
                if F[i][j]=="
                    result+=1
        print(H*W - result - count -1)
        exit()

    if Y < H-1 :
        if F[Y+1][X]=="." and reached[Y+1][X]==False:
            
            yQUE.appendleft(Y+1)
            xQUE.appendleft(X)
            cQUE.appendleft(count+1)
            reached[Y+1][X]=True
    if X < W-1 :
        if F[Y][X+1]=="." and reached[Y][X+1]==False:
            
            yQUE.appendleft(Y)
            xQUE.appendleft(X+1)
            cQUE.appendleft(count+1)
            reached[Y][X+1]=True
    if 0 < Y :
        if F[Y-1][X]=="." and reached[Y-1][X]==False:
            
            yQUE.appendleft(Y-1)
            xQUE.appendleft(X)
            cQUE.appendleft(count+1)
            reached[Y-1][X]=True
    if 0 < X :
        if F[Y][X-1]=="." and reached[Y][X-1]==False:
            
            yQUE.appendleft(Y)
            xQUE.appendleft(X-1)
            cQUE.appendleft(count+1)
            reached[Y][X-1]=True    
    try:
        bfs(yQUE.pop(),xQUE.pop(),cQUE.pop())
    except IndexError:
        print("-1")

H,W = map(int,input().split())
startY=0
startX=0
goalX=W-1
goalY=H-1
F = list(list(input()) for _ in range(H))
reached = [[False for i in range(W)] for i in range(H)]
count=0
xQUE =  deque(maxlen=1000000000)
yQUE =  deque(maxlen=1000000000)
cQUE =  deque()
bfs(startY,startX,count)

Solution (Python):
import sys
from collections import deque
from itertools import product
sys.setrecursionlimit(10**9)

H,W=map(int,input().split())
G=[[""]*W for _ in range(H)]
road=0


for y in range(H):
    s=input()
    for x in range(W):
        G[y][x]=s[x]
        if s[x]==".":
            road+=1


def bfs(pos):
    todo=[pos]
    index=1
    dx,dy=[-1,1,0,0],[0,0,-1,1]
    depth=[[0]*W for _ in range(H)]
    while True:
        x,y=pos

        
        if pos==(W-1,H-1):
            
            return depth[y][x]

        for i in range(4):
            npos=(x+dx[i],y+dy[i])
            if 0<=npos[0]<W and 0<=npos[1]<H:
                if G[npos[1]][npos[0]]=="." and not npos in todo:
                    depth[npos[1]][npos[0]]=depth[y][x]+1
                    todo.append(npos)

        if index<len(todo):
            pos=todo[index]
            index+=1
        else:
            print(-1)
            exit()
            return


d=bfs((0,0))+1

print(road-d)

Solution (Python):
import sys
from collections import deque
from itertools import product
sys.setrecursionlimit(10**9)

H,W=map(int,input().split())
G=[[""]*W for _ in range(H)]
road=0


for y in range(H):
    s=input()
    for x in range(W):
        G[y][x]=s[x]
        if s[x]==".":
            road+=1


def bfs(pos):
    todo=[pos]
    index=1
    dx,dy=[-1,1,0,0],[0,0,-1,1]
    depth=[[0]*W for _ in range(H)]
    while True:
        x,y=pos

        
        if pos==(W-1,H-1):
            
            return depth[y][x]

        for i in range(4):
            npos=(x+dx[i],y+dy[i])
            if 0<=npos[0]<W and 0<=npos[1]<H:
                if G[npos[1]][npos[0]]=="." and not npos in todo:
                    depth[npos[1]][npos[0]]=depth[y][x]+1
                    todo.append(npos)

        if index<len(todo):
            pos=todo[index]
            index+=1
        else:
            print(-1)
            exit()
            return


d=bfs((0,0))+1

print(road-d)

Solution (Python):
H, W = map(int,input().split())
s = []
black = 0
for i in range(H):
    tmp = list(input())
    s.append(tmp)
    for j in range(W):
        if tmp[j] == "
            black += 1
white = H*W - black
 
 
q = [(0,0,0)]
s[0][0] = "
while q:
    i, j, cnt = q.pop(0)
    for di, dj in [(1,0),(0,1),(-1,0),(0,-1)]:
        ni, nj = i+di, j+dj
        if ni == H-1 and nj == W-1:
            print(white-cnt-2)
            exit(0)
        elif 0 <= ni < H and 0 <= nj < W and s[ni][nj] == ".":
            s[ni][nj] = "
            q.append((ni,nj,cnt+1))
print(-1)

Solution (Python):
import numpy as np
import heapq as hp
 
H, W = map(int, input().split())
s = np.array([list(input()) for _ in range(H)])
s = np.pad(s, 1, "constant")
visited = np.zeros_like(s, dtype=np.bool)

dist = np.inf
 
h = []
hp.heappush(h, (0, 1, 1))
 
while h:
    d, x, y = hp.heappop(h)
    if x == H and y == W:
        dist = d
        break
    for dx, dy in [[0, 1], [1, 0], [-1, 0], [0, -1]]:
        nx = x + dx
        ny = y + dy
        if s[nx, ny] == "." and not visited[nx, ny]:
            visited[nx, ny] = True
            hp.heappush(h, (d + 1, nx, ny))

if dist == np.inf:
    print(-1)
else:
    print((s == ".").sum() - dist - 1)

Solution (Python):
import numpy as np
import heapq as hp

H, W = map(int, input().split())
s = np.array([list(input()) for _ in range(H)])
s = np.pad(s, 1, "constant")
visited = np.zeros_like(s, dtype=np.bool)

dist = np.inf

h = []
hp.heappush(h, (0, 1, 1))

while h:
    d, x, y = hp.heappop(h)
    if x == H and y == W:
        dist = d
        break
    for dx, dy in [[0, 1], [1, 0], [-1, 0], [0, -1]]:
        nx = x + dx
        ny = y + dy
        if s[nx, ny] == "." and not visited[nx, ny]:
            visited[nx, ny] = True
            hp.heappush(h, (d + 1, nx, ny))

if dist == np.inf:
    print(-1)
else:
    print((s == ".").sum() - dist - 1)

Solution (Python):
from collections import deque

def bfs():
    memo = [[float("inf")] * w for _ in range(h)]
    memo[0][0] = 0

    que = deque([])
    que.append((0, 0))

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

    while que:
        p = que.popleft()

        if p == (h-1, w-1):
            break

        for i in range(4):
            nx = p[0] + dx[i]
            ny = p[1] + dy[i]

            if 0 <= nx <= h-1 and 0 <= ny <= w-1 and maze[nx][ny] == "." and memo[nx][ny] == float("inf"):
                que.append((nx, ny))
                memo[nx][ny] = memo[p[0]][p[1]] + 1
    return memo[h-1][w-1]

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

black = 0
for i in range(h):
    for j in range(w):
        if maze[i][j] == "
            black += 1

root = bfs()
if root == float("inf"):
    print(-1)
else:
    print(h * w - root - black - 1)

Solution (Python):
def solve():
    s = read()
    result = think(s)
    write(result)


def read():
    h, w = read_int(2)
    s = []
    for y in range(h):
        s.append(list(read_line(w)))
    return s


def read_int(n):
    return list(map(int, read_line().split(' ')))[:n]


def read_line(n=0):
    if n == 0:
        return input().rstrip()
    else:
        return input().rstrip()[:n]


def think(s):
    w, h = get_area(s)
    gx, gy = w - 1, h - 1

    invalid = w * h
    white_tile_mark = '.'

    memo = bfs(s, w, h, white_tile_mark, invalid)

    if memo[gy][gx] == invalid:
        return -1

    shortest_path = get_shortest_path(memo, w, h, gx, gy)
    white_tiles = collect_tiles(s, white_tile_mark)
    score = 0

    for w in white_tiles:
        if w not in shortest_path:
            score += 1
    return score


def get_area(s):
    w = len(s[0])
    h = len(s)
    return w, h


def bfs(s, w, h, white_tile_mark, invalid):
    sx, sy = 0, 0

    memo = [[invalid for x in range(w)] for y in range(h)]
    queue = []
    queue.append([sx, sy, 0])

    next_steps = [[1, 0], [-1, 0], [0, 1], [0, -1]]
    while queue:
        nx, ny, nd = queue.pop(0)
        if not (0 <= nx < w and 0 <= ny < h and s[ny][nx] == white_tile_mark and memo[ny][nx] > nd):
            continue
        memo[ny][nx] = nd

        for dx, dy in next_steps:
            queue.append([nx + dx, ny + dy, nd + 1])
    return memo


def get_shortest_path(memo, w, h, gx, gy):
    next_steps = [[1, 0], [-1, 0], [0, 1], [0, -1]]
    shortest_path = []
    cx, cy = gx, gy

    while True:
        shortest_path.append([cx, cy])
        current_distance = memo[cy][cx]
        if current_distance == 0:
            break
        for dx, dy in next_steps:
            nx, ny = cx + dx, cy + dy
            if not (0 <= nx < w and 0 <= ny < h):
                continue
            if memo[ny][nx] == current_distance - 1:
                cx, cy = nx, ny
                break

    return shortest_path


def collect_tiles(s, mark):
    w, h = get_area(s)
    tiles = []
    for y in range(h):
        for x in range(w):
            if s[y][x] == mark:
                tiles.append([x, y])
    return tiles


def write(result):
    print(result)


if __name__ == '__main__':
    solve()

Solution (Python):

import sys
input = sys.stdin.readline
sys.setrecursionlimit(10**6)


from collections import deque

H, W = map(int, input().split())
maze = [ ['.' for _ in range(W)] for _ in range(H) ]
num_white = 0

for y in range(H):
    X = list(input().rstrip())
    for x in range(W):
        maze[y][x] = X[x]
        if X[x] == '.':
            num_white += 1







distance = [ [-1 for _ in range(W)] for _ in range(H) ]


def bfs(x, y):
    distance[y][x] = 0
    q = deque([(x, y)])

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

        if y > 0 and maze[y-1][x] != '
            distance[y-1][x] = distance[y][x] + 1
            q.append( (x, y-1) )
        if y < H-1 and maze[y+1][x] != '
            distance[y+1][x] = distance[y][x] + 1
            q.append( (x, y+1) )
        if x > 0 and maze[y][x-1] != '
            distance[y][x-1] = distance[y][x] + 1
            q.append( (x-1, y) )
        if x < W-1 and maze[y][x+1] != '
            distance[y][x+1] = distance[y][x] + 1
            q.append( (x+1, y) )

bfs(0, 0)
nearest = distance[H-1][W-1]


if nearest == -1:
    print(-1)
else:
    
    print (num_white - nearest - 1)

Solution (Python):
H, W = map(int,input().split())
s = []
black = 0
for i in range(H):
    tmp = list(input())
    s.append(tmp)
    for j in range(W):
        if tmp[j] == "
            black += 1
white = H*W - black


q = [(0,0,0)]
s[0][0] = "
while q:
    i, j, cnt = q.pop(0)
    for di, dj in [(1,0),(0,1),(-1,0),(0,-1)]:
        ni, nj = i+di, j+dj
        if ni == H-1 and nj == W-1:
            print(white-cnt-2)
            exit(0)
        elif 0 <= ni < H and 0 <= nj < W and s[ni][nj] == ".":
            s[ni][nj] = "
            q.append((ni,nj,cnt+1))
print(-1)

Solution (Python):
import sys
from collections import deque

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

Map = [[] for _ in range(H)]
reached = [[-1]*W for _ in range(H)]
route = [[False]*W for _ in range(H)]

q = deque()
check = False
b = 0
for y in range(H):
    for x in input():
        Map[y].append(x)
        if x=="
            b += 1

def BFS(x, y, pre):
    global check

    if x>=W or y>=H or x<0 or y<0 or Map[y][x]=="
        return

    reached[y][x] = pre + 1

    if x==(W-1) and y==(H-1):
        ans =H * W - reached[y][x] + 1 - b - 2
        print(ans)
        sys.exit()

    else:
        q.append((x + 1, y, pre + 1))
        q.append((x - 1, y, pre + 1))
        q.append((x, y + 1, pre + 1))
        q.append((x, y - 1, pre + 1))

q.append((0,0,-1))
while q:
    BFS(*q.popleft())
print(-1)

Solution (Python):



import sys
sys.setrecursionlimit(10**6)
readline = sys.stdin.readline



h,w = [int(i) for i in readline().split()]
b = [readline().strip() for _ in range(h)]

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

dx4=[0, 1, 0,-1]
dy4=[1, 0,-1, 0]



from collections import deque 




memo = [[-1]*w for _ in range(h)]
q = deque()


q.append((sx,sy)) 
memo[sx][sy] = 0 
""" "S,G"表記の場合
for i in range(h):
    for j in range(w):
        if b[i][j] == "S": 
            q.append((sx,sy)) 
            memo[sx][sy] = 0 
        if b[i][j] == "G":
            gx,gy = i,j
"""



while q: 
    x,y = q.popleft() 
    
    for i in range(4):
        nx = x + dx4[i]
        ny = y + dy4[i]
        
        if nx < 0 or nx>=h or ny <0 or ny>=w: continue
        
        if b[nx][ny] == "
        
        if memo[nx][ny] >= 0: continue
        
        memo[nx][ny] = memo[x][y]+1
        q.append((nx,ny))


res = 1+memo[gx][gy]

if res == 0:
    print(-1)
    exit()

for i in range(h):
    for j in range(w):
        if b[i][j] == ".": res -= 1

print(-res)

Solution (Python):
from collections import deque
H, W = map(int, input().split())
padding = ['
Map = tuple([padding])
Map += tuple(['
Map += tuple([padding])
dxy = [(1, 0), (-1, 0), (0, 1), (0, -1)]

done = [[-1 for _ in range(W + 2)] for _ in range(H + 2)]

q = deque()
push, pop = q.append, q.popleft
push((1, 1))
done[1][1] = 0
while q:
  y, x = pop()
  for dy, dx in dxy:
    if Map[y + dy][x + dx] == '.' and done[y + dy][x + dx] == -1:
      push((y + dy, x + dx))
      done[y + dy][x + dx] = done[y][x] + 1
  if done[H][W] != -1:
    break
    
cnt = 0
for i in range(1, H + 1):
  for j in range(1, W + 1):
    if Map[i][j] == '.':
      cnt += 1
ans = cnt - done[H][W] -1

print(ans if done[H][W] != -1 else -1)

Solution (Python):
import sys
from collections import deque
INPUT = lambda: sys.stdin.readline().rstrip()
MAP = lambda: map(int, INPUT().split())
sys.setrecursionlimit(10 ** 9)


def main():
    H, W = MAP()
    dungeon = []
    walls = 0

    for _ in range(H):
        line = [0 if i == "." else 1 for i in INPUT()]
        walls += line.count(1)
        dungeon.extend([line])

    queue = deque([(0, 0, 1)])
    while queue:
        y, x, cnt = queue.popleft()
        if y == H-1 and x == W-1:
            print(H*W - walls - cnt)
            exit()
        for row, col in [(y, x-1), (y-1, x), (y, x+1), (y+1, x)]:
            if 0 <= row < H and 0 <= col < W and not dungeon[row][col]:
                dungeon[row][col] = 2
                queue.append((row, col, cnt+1))

    print(-1)


if __name__ == '__main__':
    main()

Solution (Python):
import queue

INF = 10000000

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

d = [[INF for i in range(w)] for i in range(h)]

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

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

map = [[] for i in range(h)]
for i in range(h):
    map[i] = input()


que = queue.Queue()
que.put([sy,sx])
d[sy][sx] = 0

while not que.empty():
    p = que.get()
    if p[0] == gy and p[1] == gx:
        break
    for i in range(4):
        ny = p[0] + dy[i]
        nx = p[1] + dx[i]
        if nx<w and nx>=0 and ny<h and ny>=0 and map[ny][nx]!="
            and d[ny][nx]==INF:
            d[ny][nx] = d[p[0]][p[1]] + 1
            que.put([ny, nx])

if d[gy][gx] == INF:
    print(-1)
else:
    count = 0
    for i in range(h):
        for j in range(w):
            if map[i][j] == ".":
                count += 1
    print(count - d[gy][gx] - 1)

Solution (Python):
h, w = map(int, input().split())
b = 0
l = [0]*h
for k in range(h):
  a = str(input())
  for k_ in range(w):
    if a[k_] == '
      b += 1
  l[k] = a

 
from collections import deque
 
queue = deque()
visit = [[-1]*w for _ in range(h)]
queue.append([0, 0])
visit[0][0] = 1
 
while queue:
  y, x = queue.popleft()
  if y == h-1 and x == w-1:
    print(h*w-visit[y][x]-b)
    exit()
  for i, j in ([-1, 0], [1, 0], [0, 1], [0, -1]):
    new_y, new_x = y+i, x+j
    if (new_x>=0) and (new_x<w) and (new_y>=0) and (new_y<h) and l[new_y][new_x]=='.' and visit[new_y][new_x] == -1:
      visit[new_y][new_x] = visit[y][x]+1
      queue.append([new_y,new_x])
    else:
      continue
else:
  print('-1')

Solution (Python):
h, w = map(int, input().split())
b = 0
l = [0]*h
for k in range(h):
  a = str(input())
  for k_ in range(w):
    if a[k_] == '
      b += 1
  l[k] = a

 
from collections import deque
 
queue = deque()
visit = [[-1]*w for _ in range(h)]
queue.append([0, 0])
visit[0][0] = 1
 
while queue:
  y, x = queue.popleft()
  if y == h-1 and x == w-1:
    print(h*w-visit[y][x]-b)
    exit()
  for i, j in ([-1, 0], [1, 0], [0, 1], [0, -1]):
    new_y, new_x = y+i, x+j
    if (new_x>=0) and (new_x<w) and (new_y>=0) and (new_y<h) and l[new_y][new_x]=='.' and visit[new_y][new_x] == -1:
      visit[new_y][new_x] = visit[y][x]+1
      queue.append([new_y,new_x])
    else:
      continue
else:
  print('-1')

Solution (Python):
import sys
sys.setrecursionlimit(10**9)
from collections import deque

INF = 10**9
H,W = map(int,input().split())
G = [input() for _ in range(H)]
C = 0
for l in G:
    C += l.count("

def BFS(start,end,grid):
    queue = deque([])
    visited = []
    start += [1]
    dist = INF
    queue.append(start)
    while queue:
        label = queue.popleft()
        x = label[0]
        y = label[1]
        d = label[2]
        pos = [x,y]
        if pos == end:
            if d < dist:
                dist = d
        elif pos not in visited:
            visited.append(pos)
            if x+1 <= W-1:
                if [x+1,y] not in visited:
                    if grid[y][x+1] == ".":
                        queue.append([x+1,y,d+1])
            if x-1 >= 0:
                if [x-1,y] not in visited:
                    if grid[y][x-1] == ".":
                        queue.append([x-1,y,d+1])
            if y+1 <= H-1:
                if [x,y+1] not in visited:
                    if grid[y+1][x] == ".":
                        queue.append([x,y+1,d+1])
            if y-1 >= 0:
                if [x,y-1] not in visited:
                    if grid[y-1][x] == ".":
                        queue.append([x,y-1,d+1])
    return dist
res = BFS([0,0],[W-1,H-1],G)
if res == INF:
    print(-1)
else:
    print(H*W-res-C)

Solution (Python):
import sys
sys.setrecursionlimit(10**9)
from collections import deque

INF = 10**9
H,W = map(int,input().split())
G = [input() for _ in range(H)]
C = 0
for l in G:
    C += l.count("

def BFS(start,end,grid):
    queue = deque([])
    visited = []
    start += [1]
    dist = INF
    queue.append(start)
    while queue:
        label = queue.popleft()
        x = label[0]
        y = label[1]
        d = label[2]
        pos = [x,y]
        if pos == end:
            if d < dist:
                dist = d
        elif pos not in visited:
            visited.append(pos)
            if x+1 <= W-1:
                if [x+1,y] not in visited:
                    if grid[y][x+1] == ".":
                        queue.append([x+1,y,d+1])
            if x-1 >= 0:
                if [x-1,y] not in visited:
                    if grid[y][x-1] == ".":
                        queue.append([x-1,y,d+1])
            if y+1 <= H-1:
                if [x,y+1] not in visited:
                    if grid[y+1][x] == ".":
                        queue.append([x,y+1,d+1])
            if y-1 >= 0:
                if [x,y-1] not in visited:
                    if grid[y-1][x] == ".":
                        queue.append([x,y-1,d+1])
    return dist
res = BFS([0,0],[W-1,H-1],G)
if res == INF:
    print(-1)
else:
    print(H*W-res-C)

Solution (Python):
from collections import deque

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
H, W = map(int, input().split())
field = [input() for _ in range(H)]

dist = [[-1] * W for _ in range(H)]
que = deque()
que.append((0, 0))
dist[0][0] = 0

while len(que) > 0:
  y, x = que.popleft()
  for i in range(4):
    ny, nx = y + dy[i], x + dx[i]
    if nx < 0 or nx >= W or ny < 0 or ny >= H:
      continue
    if field[ny][nx] == '
      continue
    if dist[ny][nx] != -1:
      continue
    dist[ny][nx] = dist[y][x] + 1
    que.append((ny, nx))
    
count = sum([f.count('
      
if dist[H - 1][W - 1] != -1:
  print(H * W - count - dist[H - 1][W - 1] - 1)
else:
  print(-1)

Solution (Python):
import queue

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
H, W = map(int, input().split())
field = [input() for _ in range(H)]

dist = [[-1] * W for _ in range(H)]
que = queue.Queue()
que.put((0, 0))
dist[0][0] = 0

while not que.empty():
  y, x = que.get()
  for i in range(4):
    ny, nx = y + dy[i], x + dx[i]
    if nx < 0 or nx >= W or ny < 0 or ny >= H:
      continue
    if field[ny][nx] == '
      continue
    if dist[ny][nx] != -1:
      continue
    dist[ny][nx] = dist[y][x] + 1
    que.put((ny, nx))
    
count = sum([f.count('
      
if dist[H - 1][W - 1] != -1:
  print(H * W - count - dist[H - 1][W - 1] - 1)
else:
  print(-1)

Solution (Python):
import queue

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
H, W = map(int, input().split())
field = [input() for _ in range(H)]

dist = [[-1] * W for _ in range(H)]
que = queue.Queue()
que.put((0, 0))
dist[0][0] = 0

while not que.empty():
  y, x = que.get()
  for i in range(4):
    ny, nx = y + dy[i], x + dx[i]
    if nx < 0 or nx >= W or ny < 0 or ny >= H:
      continue
    if field[ny][nx] == '
      continue
    if dist[ny][nx] != -1:
      continue
    dist[ny][nx] = dist[y][x] + 1
    que.put((ny, nx))
    
count = 0
for y in range(H):
  for x in range(W):
    if field[y][x] == '
      count += 1
      
if dist[H - 1][W - 1] != -1:
  print(H * W - count - dist[H - 1][W - 1] - 1)
else:
  print(-1)

Solution (Python):
from collections import deque

dd = [[1, 0], [-1, 0], [0, 1], [0, -1]]
H, W = list(map(int, input().split()))
field = [input() for _ in range(H)]
def bfs():
  dist = [[float('inf')] * W for _ in range(H)]
  que = deque()
  que.append((0, 0))
  dist[0][0] = 0
  while len(que) > 0:
    y, x = que.popleft()
    if y == H - 1 and x == W - 1:
      break
    for dx, dy in dd:
      ny, nx = y + dy, x + dx
      if 0<=nx<W and 0<=ny<H and field[ny][nx]=='.' and dist[ny][nx]==float('inf'):
        dist[ny][nx] = dist[y][x] + 1
        que.append((ny, nx))
  return dist[H - 1][W - 1]
    
count = sum([f.count('
need = bfs()
      
if need == float('inf'):
  print(-1)
else:
  print(H * W - count - need - 1)

Solution (Python):
from collections import deque

R,C = list(map(int,input().split()))
Sx,Sy = 0,0
Gx,Gy = R-1,C-1
Mize = [input() for _ in range(R)]
dd = [[1, 0], [-1, 0], [0, 1], [0, -1]]

def bfs():
    d = [[float('inf')] * C for i in range(R)]
    q = deque([])
    d[Sx][Sy] = 0
    q.append((Sx,Sy))
    while(len(q) != 0):
        x,y = q.popleft()
        if x == Gx and y == Gy:
            break
        for dx,dy in dd:
            
            if -1<x+dx<R and -1<y+dy<C and Mize[x+dx][y+dy]=='.' and d[x+dx][y+dy] == float('inf'):
                q.append([x+dx,y+dy])
                d[x+dx][y+dy] = d[x][y] + 1
    return d[Gx][Gy]

white = sum([m.count('
need = bfs()
if need == float('inf'):
    print(-1)
else:
    print(R*C-white-need-1)

Solution (Python):
import sys
sys.setrecursionlimit(3000)
import queue
h,w=map(int,input().split())
s=['
l=[[0]*(w+2) for _ in [0]*(h+2)]
for i in range(h+2):
    for j in range(w+2):
        if s[i][j]=='
            l[i][j]=-1
L=queue.Queue()
L.put([1,1])
while not L.empty():
    n=L.get()
    for dx,dy in [(1,0),(-1,0),(0,1),(0,-1)]:
        if l[n[0]+dx][n[1]+dy]==0 and [n[0]+dx,n[1]+dy]!=[1,1]:
            l[n[0]+dx][n[1]+dy]=l[n[0]][n[1]]+1
            L.put([n[0]+dx,n[1]+dy])

if l[h][w]==0:print(-1)
else:print(h*w-l[h][w]-(sum(x.count('

Solution (Python):



import sys
import math
import bisect
sys.setrecursionlimit(1000000000)
from heapq import heappush, heappop,heappushpop
from collections import defaultdict
from itertools import accumulate
from collections import Counter
from collections import deque
from operator import itemgetter
from itertools import permutations
mod = 10**9 + 7
inf = float('inf')
def I(): return int(sys.stdin.readline())
def LI(): return list(map(int,sys.stdin.readline().split()))

h,w = LI()
dx = [1,0,-1,0]
dy = [0,1,0,-1]
maze = [list(input()) for _ in range(h)]
d = [[inf]*w for _ in range(h)]
d[0][0] = 1
que = deque()
que.append((0,0))
while que:
    x,y = que.popleft()
    for i in range(4):
        nx,ny = x + dx[i], y + dy[i]
        if 0 <= nx < w and 0 <= ny < h:
            if maze[ny][nx] != '
                d[ny][nx] = d[y][x] + 1
                que.append((nx,ny))

cnt = 0
for i in range(h):
    for j in range(w):
        if maze[i][j] != '
            cnt += 1
if d[-1][-1] == inf:
    print(-1)
else:
    print(cnt - d[-1][-1])

Solution (Python):
from collections import deque
import copy

H, W = map(int, input().split())
s=(0,0)
g=(H-1,W-1)
maze = [list(input()) for line in range(H)]
copied_maze = copy.deepcopy(maze)

def search(x, y):
  dq = deque()
  dq.append([x, y])
  copied_maze[x][y] = 0
  while len(dq) > 0:
    x,y = dq.popleft()
    if x==g[0] and y==g[1]:
      break
    for dx, dy in [[1,0], [0,1], [-1,0], [0,-1]]:
      nx,ny=[x+dx,y+dy]
      if 0 <= nx < H and 0 <= ny < W and copied_maze[nx][ny] != '
        dq.append([nx,ny])
        copied_maze[nx][ny] = copied_maze[x][y]+1
search(s[0],s[1])
x,y=g
cost = copied_maze[g[0]][g[1]]
if type(cost) is str:
  print(-1)
  exit()
path = {s, g}
for i in range(copied_maze[g[0]][g[1]]):
  for dx, dy in [[1,0], [0,1], [-1,0], [0,-1]]:
    nx,ny=[x+dx,y+dy]
    if 0 <= nx < H and 0 <= ny < W and copied_maze[nx][ny] == cost - 1:
      path.add((nx,ny))
      x,y=nx,ny
      cost -= 1
      break
count = 0
for i in range(H):
  for j in range(W):
    if maze[i][j] == '.' and (i, j) not in path:
      count += 1
print(count)

Solution (Python):
from collections import deque

R,C = list(map(int,input().split()))
Sx,Sy = 0,0
Gx,Gy = R-1,C-1
Mize = [input() for _ in range(R)]
dd = [[1, 0], [-1, 0], [0, 1], [0, -1]]

def bfs():
    d = [[float('inf')] * C for i in range(R)]
    q = deque([])
    d[Sx][Sy] = 0
    q.append((Sx,Sy))
    while(len(q) != 0):
        x,y = q.popleft()
        if x == Gx and y == Gy:
            break
        for dx,dy in dd:
            
            if -1<x+dx<R and -1<y+dy<C and Mize[x+dx][y+dy]=='.' and d[x+dx][y+dy] == float('inf'):
                q.append([x+dx,y+dy])
                d[x+dx][y+dy] = d[x][y] + 1
    return d[Gx][Gy]

white = sum([m.count('
need = bfs()
if need == float('inf'):
    print(-1)
else:
    print(R*C-white-need-1)