PAST3G

PAST3G

G

The problem is to find the shortest path length for a Shogi Kinsho to move from the start to the goal on a grid with obstacles.

Width-first search. One square outside the area where obstacles can be placed is sufficient for a detour route.

I first squashed the bugs while debugging output with a version in which the grid size was 5x5, since it seemed to be buggy.

The first submission exceeded the time limit because I forgot to mark the squares that had been visited. I didn't realize this when I was testing with small data.

The second submission was a run-time error, calculating the grid size one square less. There are three squares in the -1 to 1 range.

code:python

TINY_TEST = False

if TINY_TEST:

MIN_BOUND = -2

MAX_BOUND = 2

else:

MIN_BOUND = -200

MAX_BOUND = 200

WIDTH = (MAX_BOUND - MIN_BOUND) + 4 # why not 3?

def setMap(p, v):

x, y = p

def getMap(p):

x, y = p

START = (0, 0)

if TINY_TEST:

GOAL = (2, 2)

setMap(START, "S")

setMap(GOAL, "G")

for p in obstacles:

setMap(p, "#")

else:

setMap((X, Y), "G")

for i in range(N):

setMap(p, "#")

def pp(map):

for line in map:

print("".join(line))

def main():

def visit(x, y):

if getMap((x, y)) == "G":

return True

if getMap((x, y)) != ".":

return

if x < MIN_BOUND-1 or MAX_BOUND+1 < x:

return

if y < MIN_BOUND-1 or MAX_BOUND+1 < y:

return

newFront.append((x, y))

setMap((x, y), "v")

for numSteps in range(1, 1000):

front = set(newFront)

# print("len front,", len(front), numSteps)

# print(front)

newFront = []

for x, y in front:

isFinished = (

visit(x + 1, y + 1)

or visit(x, y + 1)

or visit(x - 1, y + 1)

or visit(x + 1, y)

or visit(x - 1, y)

or visit(x, y - 1))

if isFinished:

print(numSteps)

return

if not newFront:

print(-1)

return

main()

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