Problem p02644 (python)

Fixed submission:
import sys
input=sys.stdin.readline
h,w,k=map(int,input().split())
si,sj,ti,tj=map(int,input().split())
si-=1
sj-=1
ti-=1
tj-=1
b=[input()for _ in range(h)]
ans=[[-1]*w for _ in range(h)]
ans[si][sj]=0
from collections import deque
d=deque()
d.append((si,sj))
while d:
  x,y=d.popleft()
  if x==ti and y==tj:
    exit(print(ans[x][y]))
  for dx,dy in [[1,0],[-1,0],[0,-1],[0,1]]:
    for i in range(1,k+1):
      xx=x+dx*i
      yy=y+dy*i
      if not(0<=xx<h and 0<=yy<w) or b[xx][yy]=="@":break
      if 0<=ans[xx][yy]<=ans[x][y]:break
      if ans[xx][yy]==-1:d.append((xx,yy))
      ans[xx][yy]=ans[x][y]+1
print(-1)

Buggy submission (verdict: Runtime Error):
def main():
  import sys
  input=sys.stdin.readline
  h,w,k=map(int,input().split())
  sx,sy,tx,ty=map(int,input().split())
  sx-=1
  sy-=1
  tx-=1
  ty-=1
  calc=lambda x,y:x*1000007+y
  b=[]
  for i in range(h):
    s=input()
    bb=[]
    for j in s:
      if j==".":bb.append(0)
      else:bb.append(-1)
    b.append(bb)
  from collections import deque
  d=deque()
  d.append(calc(sx,sy))
  s=set()
  while d:
    x,y=divmod(d.popleft(),1000000)
    if calc(x,y)in s:
      s.discard(calc(x,y))
      continue
    if x==tx and y==ty:
      exit(print(b[x][y]))
    for i in range(1,k+1):
      if x-i<0:break
      if b[x-i][y]<=b[x][y] and b[x-i][y]!=0:break
      d.append(calc(x-i,y))
      if b[x-i][y]!=0:
        s.add(calc(x-i,y))
      b[x-i][y]=b[x][y]+1
    for i in range(1,k+1):
      if x+i==h:break
      if b[x+i][y]<=b[x][y] and b[x+i][y]!=0:break
      d.append(calc(x+i,y))
      if b[x+i][y]!=0:
        s.add(calc(x+i,y))
      b[x+i][y]=b[x][y]+1
    for j in range(1,k+1):
      if y-j<0:break
      if b[x][y-j]<=b[x][y] and b[x][y-j]!=0:break
      d.append(calc(x,y-j))
      if b[x][y-j]!=0:
        s.add(calc(x,y-j))
      b[x][y-j]=b[x][y]+1
    for j in range(1,k+1):
      if y+j==w:break
      if b[x][y+j]<=b[x][y] and b[x][y+j]!=0:break
      d.append(calc(x,y+j))
      if b[x][y+j]!=0:
        s.add(calc(x,y+j))
      b[x][y+j]=b[x][y]+1
  print(-1)
if __name__ == "__main__":
  main()

Buggy submission (verdict: Runtime Error):
def main():
  import sys
  input=sys.stdin.readline
  h,w,k=map(int,input().split())
  sx,sy,tx,ty=map(int,input().split())
  calc=lambda x,y:x*1000007+y
  b=[[-1]*(w+2)]
  for i in range(h):
    s=input()
    bb=[-1]
    for j in s:
      if j==".":bb.append(0)
      else:bb.append(-1)
    bb.append(-1)
    b.append(bb)
  b.append([-1]*(w+2))
  from collections import deque
  d=deque()
  d.append(calc(sx,sy))
  s=set()
  while d:
    x,y=divmod(d.popleft(),1000007)
    if calc(x,y)in s:
      s.discard(calc(x,y))
      continue
    if x==tx and y==ty:
      exit(print(b[x][y]))
    for i in range(1,k+1):
      if b[x-i][y]<=b[x][y] and b[x-i][y]!=0:break
      d.append(calc(x-i,y))
      if b[x-i][y]!=0:
        s.add(clac(x-i,y))
      b[x-i][y]=b[x][y]+1
    for i in range(1,k+1):
      if b[x+i][y]<=b[x][y] and b[x+i][y]!=0:break
      d.append(calc(x+i,y))
      if b[x+i][y]!=0:
        s.add(calc(x+i,y))
      b[x+i][y]=b[x][y]+1
    for j in range(1,k+1):
      if b[x][y-j]<=b[x][y] and b[x][y-j]!=0:break
      d.append(calc(x,y-j))
      if b[x][y-j]!=0:
        s.add(calc(x,y-j))
      b[x][y-j]=b[x][y]+1
    for j in range(1,k+1):
      if b[x][y+j]<=b[x][y] and b[x][y+j]!=0:break
      d.append(calc(x,y+j))
      if b[x][y+j]!=0:
        s.add(calc(x,y+j))
      b[x][y+j]=b[x][y]+1
  print(-1)
if __name__ == "__main__":
  main()