Abandoned warehouse

from queue import Queue


def make_zero_map(map):
    zero_map = []
    for i in range(len(map)):
        zero_map.append([0] * len(map[0]))
    return zero_map


def find_shortest_path(map, start, end, size):
    directions = [(0, -1), (0, 1), (-1, 0), (1, 0)]
    visited = make_zero_map(map)
    visited[start[0]][start[1]] = 1
    queue = Queue()
    queue.put((start, []))
    while not queue.empty():
        (node, path) = queue.get()
        for dx, dy in directions:
            direction = ""
            if dx == -1:
                direction = "U"
            if dx == 1:
                direction = "D"
            if dy == -1:
                direction = "L"
            if dy == 1:
                direction = "R"

            next_node = (node[0] + dx, node[1] + dy)
            if next_node == end:
                return path + [direction]
            if (next_node[0] >= 0 and next_node[1] >= 0
                and next_node[0] < size[0] and next_node[1] < size[1]
                and map[next_node[0]][next_node[1]] == '.'
                    and visited[next_node[0]][next_node[1]] == 0):
                visited[next_node[0]][next_node[1]] = 1
                queue.put((next_node, path + [direction]))


if __name__ == "__main__":
    (x, y) = map(int,  input().split())
    map = []
    start = (-1, -1)
    end = (-1, -1)

    for i in range(x):
        value = input()
        start_index = value.find('A')
        end_index = value.find('B')
        if start_index != -1:
            start = (i, start_index)
        if end_index != -1:
            end = (i, end_index)
        map.append(value)

    result = find_shortest_path(map, start, end, (x, y))
    for char in result:
        print(char, end='')
    print()

Test 1

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 58, in <module>
    for ch...

Test 2

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 58, in <module>
    for ch...

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 58, in <module>
    for ch...

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: TIME LIMIT EXCEEDED

Test 10

Verdict: TIME LIMIT EXCEEDED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: TIME LIMIT EXCEEDED

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: TIME LIMIT EXCEEDED