Abandoned warehouse

import sys
from collections import deque

input = sys.stdin.readline
n, m = map(int, input().split())

warehouse = [input().rstrip('\n') for _ in range(n)]
start = None
end = None
for i in range(n):
    row = warehouse[i]
    a = row.find('A')
    if a != -1:
        start = (i, a)
    b = row.find('B')
    if b != -1:
        end = (i, b)
if start is None or end is None:
    print("NO")
    sys.exit()

queue = deque([start])
visited = {start}
previous = {}
moves = ((-1, 0, 'U'), (1, 0, 'D'), (0, -1, 'L'), (0, 1, 'R'))

while queue and end not in visited:
    row, col = queue.popleft()
    for dr, dc, direction in moves:
        next_row, next_col = row + dr, col + dc
        next_cell = (next_row, next_col)
        if (0 <= next_row < n and 0 <= next_col < m
                and next_cell not in visited
                and warehouse[next_row][next_col] != '#'):
            visited.add(next_cell)
            previous[next_cell] = ((row, col), direction)
            queue.append(next_cell)

if end not in visited:
    print("NO")
else:
    path = []
    current = end
    while current != start:
        current, direction = previous[current]
        path.append(direction)
    path.reverse()
    print("YES")
    print(len(path))
    print(''.join(path))

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: TIME LIMIT EXCEEDED

Test 10

Verdict: TIME LIMIT EXCEEDED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: TIME LIMIT EXCEEDED