Problem: Snuke, a water strider, lives in a rectangular pond that can be seen as a grid with H east-west rows and W north-south columns. Let (i,j) be the square at the i-th row from the north and j-th column from the west.  Some of the squares have a lotus leaf on it and cannot be entered. The square (i,j) has a lotus leaf on it if c_{ij} is `@`, and it does not if c_{ij} is `.`.  In one stroke, Snuke can move between 1 and K squares (inclusive) toward one of the four directions: north, east, south, and west. The move may not pass through a square with a lotus leaf. Moving to such a square or out of the pond is also forbidden.  Find the minimum number of strokes Snuke takes to travel from the square (x_1,y_1) to (x_2,y_2). If the travel from (x_1,y_1) to (x_2,y_2) is impossible, point out that fact.

Submission attempts (in order):
def ii():return int(input())
def iim():return map(int,input().split())
def iil():return list(map(int,input().split()))
from collections import deque


def bfs(xg,yg):
    queue = deque([(xs,ys,0)])
    while queue:
        x,y,dep = queue.popleft()
        l = []
        for xx,yy in [(1,0),(0,1),(-1,0),(0,-1)]:
            for i in range(1,k+1):
                nx,ny = x+xx*i,y+yy*i
                if cord[ny][nx] == '.':
                    l.append((nx,ny))
                elif cord[ny][nx] < dep+1:
                    break
        for nx, ny in l:
            if cord[ny][nx] == '.':
                cord[ny][nx] = dep+1
                if (nx,ny) == (xg,yg):
                    return dep+1
                else:
                    queue.append((nx,ny,dep+1))
    return -1

h,w,k = iim()
ys,xs,yg,xg = iim()

cord = [['@']*(w+2)]
for i in range(h):
    cord.append(['@']+list(input())+['@'])
cord.append(['@']*(w+2))
cord[ys][xs] = '#'

print(bfs(xg,yg))


def ii():return int(input())
def iim():return map(int,input().split())
def iil():return list(map(int,input().split()))
from collections import deque


def bfs(xg,yg):
    queue = deque([(xs,ys,0)])
    update = deque()
    while queue:
        x,y,dep = queue.popleft()
        l = []
        f1 = True
        f2 = True
        f3 = True
        f4 = True
        for i in range(1,k+1):
            if f1 and cord[y][x+i] == '.':
                l.append((x+i,y))
            else:
                f1 = False
            if f2 and cord[y][x-i] == '.':
                l.append((x-i,y))
            else:
                f2 = False
            if f3 and cord[y+i][x] == '.':
                l.append((x,y+i))
            else:
                f3 = False
            if f4 and cord[y-i][x] == '.':
                l.append((x,y-i))
            else:
                f4 = False
            if not (f1 or f2 or f3 or f4):
                break
        for nx, ny in l:
            if cord[ny][nx] == '.':
#                cord[ny][nx] = (dep+1)%10
                if (nx,ny) == (xg,yg):
                    cord[ny][nx] = 'G'
                    return dep+1
                else:
                    update.append((nx,ny))

        while update:
            x,y = update.popleft()
            cord[y][x] = '#'
            queue.append((nx,ny,dep+1))

    return -1

h,w,k = iim()
ys,xs,yg,xg = iim()

cord = [['@']*(w+2)]
for i in range(h):
    cord.append(['@']+list(input())+['@'])
cord.append(['@']*(w+2))
cord[ys][xs] = 'S'

print(bfs(xg,yg))


def ii():return int(input())
def iim():return map(int,input().split())
def iil():return list(map(int,input().split()))
from collections import deque


def bfs(xg,yg):
    queue = deque([(xs,ys,0)])
    while queue:
        x,y,dep = queue.popleft()
        l = []
        f1 = True
        f2 = True
        f3 = True
        f4 = True
        for i in range(1,k+1):
            if f1 and cord[y][x+i] == '.':
                l.append((x+i,y))
            elif cord[y][x+i] == '@':
                f1 = False
            if f2 and cord[y][x-i] == '.':
                l.append((x-i,y))
            elif cord[y][x-i] == '@':
                f2 = False
            if f3 and cord[y+i][x] == '.':
                l.append((x,y+i))
            elif cord[y+i][x] == '@':
                f3 = False
            if f4 and cord[y-i][x] == '.':
                l.append((x,y-i))
            elif cord[y-i][x] == '@':
                f4 = False
            if not (f1 or f2 or f3 or f4):
                break
        for nx, ny in l:
            if cord[ny][nx] == '.':
                cord[ny][nx] = '#'
                if (nx,ny) == (xg,yg):
                    return dep+1
                else:
                    queue.append((nx,ny,dep+1))
    return -1

h,w,k = iim()
ys,xs,yg,xg = iim()

cord = [['@']*(w+2)]
for i in range(h):
    cord.append(['@']+list(input())+['@'])
cord.append(['@']*(w+2))
cord[ys][xs] = '#'

#    print(*i)
print(bfs(xg,yg))

def ii():return int(input())
def iim():return map(int,input().split())
def iil():return list(map(int,input().split()))
from collections import deque


def bfs(xg,yg):
    queue = deque([(xs,ys,0)])
    while queue:
        x,y,dep = queue.popleft()
        l = []
        for xx,yy in [(1,0),(0,1),(-1,0),(0,-1)]:
            for i in range(1,k+1):
                nx,ny = x+xx*i,y+yy*i
                if cord[ny][nx] == '.':
                    l.append((nx,ny))
                elif type(cord[ny][nx]) != int or cord[ny][nx] < dep+1:
                    break
        for nx, ny in l:
            if cord[ny][nx] == '.':
                cord[ny][nx] = dep+1
                if (nx,ny) == (xg,yg):
                    return dep+1
                else:
                    queue.append((nx,ny,dep+1))
    return -1

h,w,k = iim()
ys,xs,yg,xg = iim()

cord = [['@']*(w+2)]
for i in range(h):
    cord.append(['@']+list(input())+['@'])
cord.append(['@']*(w+2))
cord[ys][xs] = '#'

print(bfs(xg,yg))


Verdicts: Runtime Error

Wrong Answer

Runtime Error

Accepted