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



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


Sample output:
2

Submission status: Accepted

Solution code:
from collections import deque

def bfs(maze,visited,sy,sx,gy,gx):
    Step = ([1,0],[0,1],[-1,0],[0,-1])
    
    que = deque([[sx,sy]])
    visited[sx][sy] = 1
    
    while que:
        y,x = que.popleft()
        if [y,x] == [gy,gx]:
            return visited[y][x]
        for j,k in Step:
            ny,nx = y+j , x+k
            if 0 <= ny <= gy and 0 <= nx <= gx:
                if maze[ny][nx] == '.' and visited[ny][nx] == INF:
                    visited[ny][nx] = visited[y][x] + 1
                    que.append([ny,nx])


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

cntSharp = 0
for i in range(h):
    cntSharp += maze[i].count('.')

INF = 10**5
visited = [[INF]*w for _ in range(h)]

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

minStep = bfs(maze,visited,sy,sx,gy,gx)
print(cntSharp - minStep if visited[gy][gx] != INF else -1)

Submission status: Accepted

Solution code:
n,m=map(int,input().split())
mat=[]
blk=0 
for i in range(n):
    mat.append(list(input()))
for i in range(n):
    for j in range(m):
        if mat[i][j]=='.':
            mat[i][j]=0 
        else:
            mat[i][j]=1 
            blk+=1 
vis=[[0 for j in range(m)]for i in range(n)]
dist=[[-1 for j in range(m)]for i in range(n)]
q=[[0,0]]
dx=[0,0,1,-1]
dy=[-1,1,0,0]
if mat[0][0] or mat[n-1][m-1]:
    print(-1)
    exit()
dist[0][0]=0 
while q: 
    t=q.pop(0)
    x=t[0]
    y=t[1]
    for i in range(4):
        if 0<=x+dx[i]<n and 0<=y+dy[i]<m and vis[x+dx[i]][y+dy[i]]==0 and mat[x+dx[i]][y+dy[i]]==0:
            vis[x+dx[i]][y+dy[i]]=1 
            q.append([x+dx[i],y+dy[i]])
            dist[x+dx[i]][y+dy[i]]=dist[x][y]+1 
if not vis[n-1][m-1]:
    print(-1)
    exit()
print(n*m-dist[n-1][m-1]-blk-1)

Submission status: Accepted

Solution code:
from collections import deque

H , W = map(int,input().split())
maze = []
white_cnt = -1
for _ in range(H):
    row = list(input())
    white_cnt += row.count(".")
    maze.append(row)

def bfs(sy,sx,gy,gx , ma):
    dx = [0,1,0,-1]
    dy = [1,0,-1,0]
    score = [[-1 for _ in range(W)] for _ in range(H)]
    score[sy][sx] = 0
    q = deque()
    q.append([sy,sx])
    while q:
        now_y , now_x = q.popleft()
        for i in range(4):
            next_y , next_x = now_y + dy[i] , now_x + dx[i]
            if 0 <= next_y and next_y < H and 0 <= next_x and next_x < W and score[next_y][next_x] == -1 and ma[next_y][next_x] == ".":
                q.append([next_y,next_x])
                score[next_y][next_x] = score[now_y][now_x] + 1
    return score[gy][gx]


min_distance = bfs(0 , 0,H - 1,W - 1 , maze)
if min_distance == -1:
    print(min_distance)
else:
    print(white_cnt - min_distance)

Submission status: Accepted

Solution code:
from collections import deque
h,w = map(int,input().split())
list1 = [list(input()) for i in range(h) ]
visited = [[-1]*w for i in range(h)]
black_count = 0
for i in range(h):
	black_count += list1[i].count("#")
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 <= new_y < h and \
				0 <= new_x < w and\
				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])
	return -1

shortest = bfs(list1,visited,0,0,h-1,w-1)
if shortest == -1:
	print(-1)
	exit()
print(h*w - black_count - shortest-1) #-1はスタート地点

Submission status: Accepted

Solution code:
r,c=map(int,input().split())
meiro=[list(input()) for i in range(r)]
#迷路の白マスを数える作業
white=0
for i in range(r):
    for j in range(c):
        if meiro[i][j]==".":
            white+=1
#迷路の外を＃で囲む
for i in range(r):
    meiro[i].insert(c,"#")
    meiro[i].insert(0,"#")
meiro.insert(0,["#"]*(c+2))
meiro.append(["#"]*(c+2))
#print(meiro)囲えた
idou=[[0,1],[0,-1],[1,0],[-1,0]]
tesuu=[[-1]*(c+2) for i in range(r+2)]
from collections import deque
tesuu[1][1]=1
#print(tesuu)
quest=deque([[1,1]])#最初に見る場所
while len(quest)!=0:
    see=quest.popleft()
    for i in idou:
        if meiro[see[0]+i[0]][see[1]+i[1]]=="#":
            continue
        if tesuu[see[0]+i[0]][see[1]+i[1]]!=-1:
            continue
        quest.append([see[0]+i[0],see[1]+i[1]])
        tesuu[see[0]+i[0]][see[1]+i[1]]=tesuu[see[0]][see[1]]+1
#print(meiro)
#print(tesuu[r][c])
gy=r;gx=c
if tesuu[gy][gx]==-1:
    print(-1)
else:
    print(white-tesuu[gy][gx])

Submission status: Accepted

Solution code:
from collections import deque
H, W = map(int, input().split())
S = []
w = 0
for i in range(H):
    s = input()
    w += s.count(".")
    S.append(list(s))

Q = deque([(0, 0, 0)])
ans = float("inf")
flag = False
while Q:
    i, j, n = Q.popleft()
    if i == H-1 and j == W-1:
        flag = True
        ans = min(ans, n)
    if S[i][j] == ".":
        S[i][j] = "#"
        for dx, dy in [(1, 0), (0, 1), (-1, 0), (0, -1)]:
            if 0 <= i + dx < H and 0 <= j + dy < W:
                Q.append((i+dx, j+dy, n+1))
if flag:
    print((w-2)-(ans-1))
else:
    print(-1)

Submission status: Accepted

Solution code:
from collections import deque

H, W = map(int, input().split())
sy = 0
sx = 0
gy = H-1
gx = W-1
c = []
d = [[-1 for i in range(W)] for j in range(H)]
d[sy][sx] = 0
cnt=0
for i in range(H):
	c.append(input())
for j in range(H):
  cnt=cnt+c[j].count(".")

dirr = [[1, 0], [0, 1], [-1, 0], [0, -1]]
q = deque()
q.append([sy, sx, 0])
while len(q) != 0:
	y, x, w = q[0]
	if y == gy and x == gx:
		break

	for i in range(4):
		ny, nx = y + dirr[i][0], x + dirr[i][1]
		if ny>=0 and nx>=0 and ny<H and nx<W and d[ny][nx] == -1 and c[ny][nx] != "#":
			q.append([ny, nx, w + 1])
			d[ny][nx] = w + 1

	q.popleft()

if d[gy][gx]==-1:
  print(-1)
else:
  print(cnt-w-1)

Submission status: Accepted

Solution code:
#!/usr/bin/env python3
from collections import deque

def main():
    H,W = map(int,input().split())
    S = [list(input()) for _ in range(H)]
    white_count = 0

    for s in S:
        for ss in s:
            if ss == ".":
                white_count+=1

    vector = [[1,0],[-1,0],[0,-1],[0,1]]
    min_distance = [[float('inf')]*W for _ in range(H)]
    queue = deque([[0,0]])
    min_distance[0][0] = 0

    while queue:
        q = queue.popleft()
        for v in vector:
            nqy = q[0]+v[0]
            nqx = q[1]+v[1]

            if nqx>=0 and nqy>=0 and nqx<=W-1 and nqy<=H-1 and min_distance[nqy][nqx]==float('inf') and S[nqy][nqx]!="#":
                queue.append([nqy,nqx])
                min_distance[nqy][nqx]=min_distance[q[0]][q[1]]+1

    if min_distance[H-1][W-1] == float('inf'):
        print(-1)
    else:
        print(white_count - min_distance[H-1][W-1]-1)



if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
from collections import deque
H,W=map(int,input().split())

l=[input() for _ in range(H)]

sx,sy=0,0

black=0
for i in range(H):
  for j in range(W):
    if l[i][j]=='#':
      black+=1

def bfs(sx,sy,l):
  que=deque()
  que.append([sx,sy])
  count=[[-1]*W for _ in range(H)]
  count[sx][sy]=0
  dx=[1,-1,0,0]
  dy=[0,0,1,-1]
  while que:
    x,y=que.popleft()
    if x==H-1 and y==W-1:
      return count[x][y]
    for j in range(4):
      a,b=x+dx[j],y+dy[j]
      if a<0 or a>=H or b<0 or b>=W or count[a][b]!=-1 or l[a][b]=='#':
        continue
      else:
        count[a][b]=count[x][y]+1
        que.append([a,b])
  return 0
print(-1 if bfs(sx,sy,l)==0 else H*W-(bfs(sx,sy,l)+black+1))

Submission status: Accepted

Solution code:
from collections import deque
import itertools

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

s = []
for _ in range(H):
    s.append(input())

sx, sy = 0, 0
gx, gy = W - 1, H - 1

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

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

diff = [[-1, 0], [1, 0], [0, -1], [0, 1]]

while len(d) != 0:
    y, x = d.popleft()

    for dy, dx in diff:
        ny, nx = y + dy, x + dx
        if nx >= 0 and ny >= 0 and nx < W and ny < H and s[ny][nx] != '#' and score[ny][nx] == -1:
            score[ny][nx] = score[y][x] + 1
            d.append([ny, nx])

min_cell = score[gy][gx]
if min_cell != -1:
    whites = list(itertools.chain.from_iterable(s)).count('.')

    repaintings = whites - min_cell - 1
    print(repaintings)
else:
    print(-1)

Submission status: Accepted

Solution code:
from collections import deque

h, w = map(int, input().split())
c = []
d = [[-1 for i in range(w)] for j in range(h)]
d[0][0] = 0
white = 0
for i in range(h):
	s = input()
	c.append(s)
	white += s.count('.')

dirr = [[1, 0], [0, 1], [-1, 0], [0, -1]]
q = deque()
q.append([0, 0, 0])

min_dist = -1
while len(q) != 0:
	y, x, z = q[0]
	if y == h - 1 and x == w - 1:
		min_dist = z
		break

	for i in range(4):
		ny, nx = y + dirr[i][0], x + dirr[i][1]
		if 0 <= ny < h and 0 <= nx < w and d[ny][nx] == -1 and c[ny][nx] != "#":
			q.append([ny, nx, z + 1])
			d[ny][nx] = z + 1

	q.popleft()

if min_dist == -1:
	print(-1)
else:
	print(white - min_dist - 1)

Submission status: Accepted

Solution code:
import collections
h, w = list(map(int, input().split()))
inf = h * w + 1
sharp = 0
data = []
for i in range(h):
    data.append(list(input()))
    # #の数を数えておく
    sharp += data[i].count('#')

ans = [[inf for i in range(w)] for j in range(h)]
def dfs(row, column, count,data):
    #もし配列の外を参照しているようであれば終了させる
    if(row > w - 1) or (column > h - 1) or ( row < 0 ) or ( column < 0 ):
        return

    if data[column][row] == '#':
        return
    data[column][row] == '#'
    #探索済みなので＃を入れたが、もっと良い方法があるかもしれない
    count += 1
    if row == w - 1 and column == h - 1:
        ans[column][row] = min(count, ans[column][row])
        return
    #その場所がゴールならば終了。ansにそこまでのコストを追加
    ##dataの写しを引数として渡したい。参照渡しか値渡しかを確認
    #+-1ずつ四方向に全探索
    dfs(row + 1, column,     count, data)
    dfs(row,     column + 1, count, data)
    dfs(row - 1, column,     count, data)
    dfs(row,     column - 1, count, data)
def bfs(row, column, count,data):
    becter = [-1,1]
    queue = collections.deque()
    queue.append([column, row,count])
    while len(queue) != 0:
        v = queue.popleft()
        if v[0] < 0 or v[1] < 0 or v[0] >= h or v[1] >= w:
            continue
        if data[v[0]][v[1]] != '#':

            data[v[0]][v[1]] = '#'
            v[2] += 1
            ans[v[0]][v[1]] = min(ans[v[0]][v[1]], v[2])
            queue.append([v[0] + 1, v[1],v[2]])
            queue.append([v[0], v[1] + 1,v[2]])
            queue.append([v[0] - 1, v[1],v[2]])
            queue.append([v[0], v[1] - 1,v[2]])


bfs(0, 0, 0,data)
if ans[-1][-1] == inf:
    print(-1)
    exit()
print(h * w - sharp - ans[-1][-1])

Submission status: Accepted

Solution code:
import sys
sys.setrecursionlimit(1000000)
from collections import deque
h,w=map(int,input().split())
s=[list(input()) for i in range(h)]
c=0
for i in range(w):
    for j in range(h):
        if s[j][i]=='.':
            c+=1
def bfs():
    d=[[float('inf')]*w for i in range(h)]
    dx=[1,0,-1,0]
    dy=[0,1,0,-1]
                
    que=deque([])
    que.append((0,0))
    d[0][0]=0
    
    while que:
        p=que.popleft()
        if p[0]==h-1 and p[1]==w-1:
            print(c-d[h-1][w-1]-1)
            exit()
        for i in range(4):
            nx=p[0]+dx[i]
            ny=p[1]+dy[i]
            
            if 0<=nx and nx<h and 0<=ny and ny<w and s[nx][ny]!='#' and d[nx][ny]==float('inf'):
                que.append((nx,ny))
                d[nx][ny]=d[p[0]][p[1]]+1
    print(-1)

bfs()

Submission status: Accepted

Solution code:
from collections import deque
h,w=map(int,input().split())
field=[["#" for i in range(w+2)]]+[["#"]+list(input())+["#"] for i in range(h)]+[["#" for i in range(w+2)]]
queue=deque([[1,1]])
cost=[[50000 for i in range(w)]for j in range(h)]
cost[0][0]=0
while queue:
  now=queue.popleft()
  for i in [(-1,0),(1,0),(0,1),(0,-1)]:
    if field[now[0]+i[0]][now[1]+i[1]]=="#":continue
    if cost[now[0]+i[0]-1][now[1]+i[1]-1]!=50000:continue
    queue.append((now[0]+i[0],now[1]+i[1]))
    cost[now[0]+i[0]-1][now[1]+i[1]-1]=cost[now[0]-1][now[1]-1]+1
cnt=0
for i in range(h+2):
  for j in range(w+2):
    if field[i][j]=="#":cnt+=1
cnt-=(h+w)*2+4
blackable=h*w-cnt
if cost[-1][-1]==50000:print(-1)
else:
  print(blackable-cost[-1][-1]-1)

Submission status: Accepted

Solution code:
import sys
from collections import defaultdict

input = sys.stdin.readline


class AtCoder:
    def main(self):
        H, W = map(int, input().split())
        field = defaultdict(lambda: '#')
        dot_cnt = 0
        for h in range(H):
            for w, c in enumerate(list(input().rstrip())):
                field[str(h + 1) + '-' + str(w + 1)] = c
                if c == '.':
                    dot_cnt += 1

        q = [(1, 1)]
        field['1-1'] = '#'
        moving_range = ((1, 0), (-1, 0), (0, 1), (0, -1))
        moves = 1
        while q:
            if (H, W) in q:
                break

            next_q = []
            for x, y in q:
                for m_x, m_y in moving_range:
                    n_x, n_y = x + m_x, y + m_y
                    if field[str(n_x) + '-' + str(n_y)] == '.':
                        next_q.append((n_x, n_y))
                        field[str(n_x) + '-' + str(n_y)] = '#'
            moves += 1
            q = next_q
            if not q:
                print(-1)
                exit()

        print(dot_cnt - moves)


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

Submission status: Accepted

Solution code:
import sys
from collections import defaultdict

input = sys.stdin.readline


class AtCoder:
    def main(self):
        H, W = map(int, input().split())
        field = defaultdict(lambda: '#')
        dot_cnt = 0
        for h in range(H):
            for w, c in enumerate(list(input().rstrip())):
                field[str(h + 1) + '-' + str(w + 1)] = c
                if c == '.':
                    dot_cnt += 1

        q = [(1, 1)]
        field['1-1'] = '#'
        moving_range = ((1, 0), (-1, 0), (0, 1), (0, -1))
        moves = 1
        goal_is_reachable = False
        while q:
            if (H, W) in q:
                goal_is_reachable = True
                break

            next_q = []
            for x, y in q:
                for m_x, m_y in moving_range:
                    n_x, n_y = x + m_x, y + m_y
                    if field[str(n_x) + '-' + str(n_y)] == '.':
                        next_q.append((n_x, n_y))
                        field[str(n_x) + '-' + str(n_y)] = '#'
            moves += 1
            q = next_q

        if not goal_is_reachable:
            print(-1)
        else:
            print(dot_cnt - moves)


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

Submission status: Accepted

Solution code:
from collections import deque

h, w = map(int, input().split())
INF = float("inf")
vect = ((0, 1), (0, -1), (1, 0), (-1, 0))
field = [[INF] * w for _ in range(h)]
bcnt = 0

for i in range(h):
    for j, s in enumerate(input()):
        if s == "#":
            field[i][j] = -1
            bcnt += 1

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

while q:
    y, x = q.popleft()
    if y == h-1 and x == w-1: break
    for dy, dx in vect:
        ny, nx = y + dy, x + dx
        if ny < 0 or ny >= h or nx < 0 or nx >= w or field[ny][nx] != INF: continue
        q.append((ny, nx))
        field[ny][nx] = field[y][x] + 1

res = field[h-1][w-1]
if res == INF or res == -1: print(-1)
else: print(h*w - bcnt - (res + 1))

Submission status: Accepted

Solution code:
from collections import deque
import sys
input = sys.stdin.readline

H, W = map(int, input().split())
c = [['#'] + list(input()) + ['#'] for i in range(H)]
c = [['#'] * (W + 2)] + c + [['#'] * (W + 2)]

# 縦方向をy, 横方向をxとする
sx, sy, gx, gy = 1, 1, W, H
ans = 0

visited = [[-1] * (W + 2) for _ in range(H + 2)]
# 未訪問は-1とする。訪問後は距離で上書きしていく

queue = deque([[sy, sx]])
# 次に探索すべきマスを追加していく用

visited[sy][sx] = 1
# スタート地点は訪問済み

shortest = H * W

while queue:
    # queueが空になるまで,つまり訪問すべきマスがなくなるまで行う
    y, x = queue.popleft()
    if [y, x] == [gy, gx]:
        shortest = visited[y][x]
        break

    for i, j in ([1, 0], [-1, 0], [0, 1], [0, -1]):
        new_y, new_x = y + j, x + i
        if c[new_y][new_x] == '.' and visited[new_y][new_x] == -1:
            # もし上下左右のマスが移動可能かつ未訪問だったら
            visited[new_y][new_x] = visited[y][x] + 1
            # [new_y][new_x]は今いる場所から+1の距離
            queue.append([new_y, new_x])
            # 訪問すべきマスとして追加
else:
    print(-1)
    exit()

print(sum([i.count('.') for i in c]) - shortest)

Submission status: Accepted

Solution code:
h, w = map(int, input().split())
s = [['#'] * (w + 2)] + [['#'] + list(input()) + ['#'] for i in range(h)]\
    + [['#'] * (w + 2)]
p = [[1, 1]]
d = 0
for i in range(1, h+1):
    for j in range(1, w+1):
        if s[i][j] == '.':
            d += 1
s[1][1] = '#'
k = 0
while [h, w] not in p:
    k += 1
    g = []
    for i in range(len(p)):
        x, y = p[i][0], p[i][1]
        if s[x-1][y] == '.':
            s[x-1][y] = 'Q'
            g.append([x-1, y])
        if s[x+1][y] == '.':
            s[x+1][y] = 'Q'
            g.append([x+1, y])
        if s[x][y+1] == '.':
            g.append([x, y+1])
        if s[x][y-1] == '.':
            s[x][y-1] = 'Q'
            g.append([x, y-1])
    else:
        p = g
        if len(p) == 0:
            print(-1)
            break
else:
    print(d - k - 1)

Submission status: Accepted

Solution code:
h,w=map(int,input().split())
s=[]
for i in range(h):
	x=input()
	s.append(x)
inf=1000
dis=[[inf for _ in range(w)]for _ in range(h)]
dis[0][0]=0
lis=[[0,0]]
for i in range(1,101):
	p=[]
	for j in range(len(lis)):
		if lis[j][1]-1>=0:
			if s[lis[j][0]][lis[j][1]-1]=="." and dis[lis[j][0]][lis[j][1]-1]==1000:
				p.append([lis[j][0],lis[j][1]-1])
				dis[lis[j][0]][lis[j][1]-1]=min(i,dis[lis[j][0]][lis[j][1]-1])
		if lis[j][1]+1<w:
			if s[lis[j][0]][lis[j][1]+1]=="." and dis[lis[j][0]][lis[j][1]+1]==1000:
				p.append([lis[j][0],lis[j][1]+1])
				dis[lis[j][0]][lis[j][1]+1]=min(i,dis[lis[j][0]][lis[j][1]+1])
		if lis[j][0]-1>=0:
			if s[lis[j][0]-1][lis[j][1]]=="." and dis[lis[j][0]-1][lis[j][1]]==1000:
				p.append([lis[j][0]-1,lis[j][1]])
				dis[lis[j][0]-1][lis[j][1]]=min(i,dis[lis[j][0]-1][lis[j][1]])
		if lis[j][0]+1<h:
			if s[lis[j][0]+1][lis[j][1]]=="." and dis[lis[j][0]+1][lis[j][1]]==1000:
				p.append([lis[j][0]+1,lis[j][1]])
				dis[lis[j][0]+1][lis[j][1]]=min(i,dis[lis[j][0]+1][lis[j][1]])
	if dis[-1][-1]!=1000:
		break
	lis=p
cnt=0
for i in range(h):
	cnt+=s[i].count(".")
if dis[-1][-1]==1000:
	print(-1)
	exit()
print(cnt-dis[-1][-1]-1)

Submission status: Accepted

Solution code:
import sys
import os
from collections import deque

INF = 10**5
H, W = map(int,input().split())
S = ["" for _ in range(H)]
cntSharp = 0
for i in range(H):
    S[i] = input()
    cntSharp += S[i].count("#")

dp = [[INF for _ in range(W)] for _ in range(H)]
dp[0][0] = 0
#移動用のベクトル
dx = [1,0,-1,0]
dy = [0,1,0,-1]
P = deque([])
P.append((0,0))
while P:
    p = P.popleft()
    s,t = p[0], p[1]
    for i in range(4):
        nx,ny = s + dx[i], t + dy[i]
        if 0 <= nx and 0 <= ny and nx <= H-1 and ny <= W-1 and S[nx][ny] =="." and dp[nx][ny] == INF:
            dp[nx][ny] = dp[s][t] + 1
            P.append((nx,ny))
if dp[H-1][W-1] == INF:
    print(-1)
else:
    print(H*W - dp[H-1][W-1] - cntSharp - 1)

Submission status: Accepted

Solution code:
from collections import deque

H, W = map(int, input().split())
S = ['#'*(W+2)]
white_num = 0
for _ in range(H):
    s = input()
    white_num += s.count('.')
    S.append('#'+s+'#')
S.append('#'*(W+2))

C = [[-1]*(W+2) for _ in range(H+2)]
C[1][1] = 1
q = deque()
q.append((1, 1))
xlist = [0, 0, 1, -1]
ylist = [1, -1, 0, 0]
while len(q) > 0:
    x, y = q.popleft()
    for i in range(4):
        mx = x + xlist[i]
        my = y + ylist[i]
        if S[mx][my] == '#' or C[mx][my] >= 0:
            continue
        C[mx][my] = C[x][y] + 1
        q.append((mx, my))
if C[H][W] == -1:
    print(-1)
else:
    print(white_num - C[H][W])

Submission status: Accepted

Solution code:
def main():
    H, W = (int(i) for i in input().split())
    c = [input() for j in range(H)]
    sh, sw = 0, 0
    gh, gw = H-1, W-1

    from collections import deque
    def bfs():
        que = deque()
        dist = [[-1]*W for i in range(H)]

        dist[sh][sw] = 0
        que.append((sh,sw))
        d = ((1,0),(0,1),(-1,0),(0,-1))
        while que:
            uy,ux = que.popleft()
            for dy, dx in d:
                next_y = uy + dy
                next_x = ux + dx
                if not(0 <= next_y < H and 0 <= next_x < W): continue
                if dist[next_y][next_x] != -1: continue
                if c[next_y][next_x] == '#': continue
                dist[next_y][next_x] = dist[uy][ux] + 1
                que.append((next_y, next_x))
                if next_y == gh and next_x == gw:
                    return dist[gh][gw]
        return -1

    white_cnt = -1
    for i in range(H):
        for j in range(W):
            if c[i][j] == '.': white_cnt += 1
    
    goal = bfs()
    print(white_cnt - goal if goal != -1 else -1)

if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
from collections import deque

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

INF = 10 ** 5
d = [[INF for i in range(W)] for j in range(H)]
d[0][0] = 0
nexts = [(-1, 0), (1, 0), (0, -1), (0, 1)]
q = deque()
q.append((0, 0))
while len(q) > 0:
  x, y = q.popleft()
  for dx, dy in nexts:
    nx, ny = x+dx, y+dy
    if nx < 0 or nx >= W or ny < 0 or ny >= H:
      continue
    if M[ny][nx] == '#' or d[ny][nx] != INF:
      continue
    d[ny][nx] = d[y][x] + 1
    q.append((nx, ny))

if d[H-1][W-1] == INF:
  print(-1)
else:
  res = 0
  for y in range(H):
    for x in range(W):
      if M[y][x] == '.':
        res += 1
  print(res-(d[H-1][W-1]+1))

Submission status: Accepted

Solution code:
from collections import deque

h, w = map(int, input().split())
s = [list(input()) for i in range(h)]
count = 0
for i in s:
    for j in range(w):
        if i[j] == "#":
            count += 1

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

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

    while que:

        p = que.popleft()

        if p[0] == h - 1 and p[1] == w - 1:
            break

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

            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and d[nx][ny] == float("inf"):
                
                que.append((nx, ny))
                d[nx][ny] = d[p[0]][p[1]] + 1

    return d[h - 1][w - 1]

ans = bfs()
if ans == float("inf"):
    print(-1)
else:
    print((h*w) - (ans+1) - count)

Submission status: Accepted

Solution code:
from collections import deque

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

gx, gy = w-1, h-1

q = deque()
q.appendleft([0,0])
INF = 10**5

dist = [[INF]*w for _ in range(h)]
dist[0][0] = 0

while q:
  x,y = q.pop()
  
  for dx,dy in [[1,0],[0,1],[-1,0],[0,-1]]:
    nx = x+dx
    ny = y+dy
    
    if 0<=nx<w and 0<=ny<h:
      if dist[ny][nx]==INF and maze[ny][nx] != '#':
        dist[ny][nx] = dist[y][x]+1
        q.appendleft([nx,ny])      

black_num = sum([maze[i].count('#') for i in range(h)])

if dist[gy][gx] == INF:
  print(-1)
else:  
  print( h*w - dist[gy][gx] - black_num -1 )

Submission status: Accepted

Solution code:
H, W = map(int, input().split())
maze = [input() for _ in range(H)]
p_flg = [[0]*W for _ in range(H)]
dyx = [(-1,0),(1,0),(0,-1),(0,1)]

def bfn(y,x,cnt):
    stack = [(y,x,cnt)]
    p_flg[y][x] = cnt
    while stack:
        sy, sx, cnt= stack.pop(0)
        cnt += 1
        for dy, dx in dyx:
            ny, nx = sy+dy, sx+dx
            if ny == H-1 and nx == W-1:
                return cnt
            elif 0<=ny<H and 0<=nx<W:
                if maze[ny][nx] !="#" and not p_flg[ny][nx]:
                    p_flg[ny][nx] = cnt
                    stack.append((ny,nx,cnt))
    return 0

def main():
    n_obs = 0
    for h in range(H):
        for w in range(W):
            if maze[h][w] == "#":
                n_obs += 1
    n_path = bfn(0,0,1) -1
    if n_path == -1:
        print(-1)
        return
    else:
        ans = H*W - n_obs - n_path -1
        print(ans)

if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
h,w=map(int,input().split())
b=[["#"]*(w+2)]
a=0
for i in range(h):
  c=["#"]
  for j in input():
    a+=j=="#"
    c.append(j)
  b.append(c+["#"])
b+=[["#"]*(w+2)]
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)

Submission status: Accepted

Solution code:
# 必要なライブラリのインポート
import queue


def f(x,y):
    if x < 0 or y < 0 or x >= r or y >= c:
        return False
    if m[x][y] == "#":
        return False
    elif not (x,y) in done:
        if (x,y) == (gx,gy):
            return True
        else:
            done.add((x,y))
            q.put((x,y))
            return False
    else:
        return False          

# FIFOキューの作成
q = queue.Queue()

r,c = map(int,input().split())
sx,sy = 1,1
gx,gy = r,c

sx -= 1
sy -= 1
gx -= 1
gy -= 1


m = ["" for _ in range(r)] 
sharp_counter = 0
for i in range(r):
    m[i] = input()
    sharp_counter += m[i].count("#")
    
    
q.put((sx,sy))
done = set()
counter = 1
while True:
    q_list = []
    for _ in range(q.qsize()):
        tx,ty = q.get()
        q_list.append((tx,ty))
        
    for one in q_list:
        tx,ty = one
        flags = [f(tx,ty-1),f(tx,ty+1),f(tx-1,ty),f(tx+1,ty)]
        if sum(flags) == 1:
            print(r*c -sharp_counter -(counter-1)-2)
            break
            
    if sum(flags) == 1:
        break
    if q_list == []:
        print(-1)
        break
    else:
        counter += 1

Submission status: Accepted

Solution code:
#!/usr/bin/env python3
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()

Submission status: Accepted

Solution code:
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("#") for l in maze])
        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()