Abandoned warehouse

inp = input().split(" ")

r, c = (int(inp[0]), int(inp[1]))

map = [[] for _ in range(r)]
seen = [[0 for _ in range(c)] for _ in range(r)]

start = (0, 0)
end = (0, 0)

for i in range(r):
    line = list(input())
    for j in range(len(line)):
        map[i].append(line[j])
        if line[j] == "A":
            start = (i, j)
        elif line[j] == "B":
            end = (i, j)

# perform bfs on the map
seen[start[0]][start[1]] = 1
q = []

q.append(("", start))
while len(q) > 0:
    cur = q.pop(0)

    cur_str = cur[0]
    cur_y, cur_x = cur[1]

    if map[cur_y][cur_x] == "B":
        print("YES")
        print(len(cur_str))
        print(cur_str)
        quit()

    # check up
    if (
        cur_y - 1 >= 0
        and seen[cur_y - 1][cur_x] == 0
        and (map[cur_y - 1][cur_x] == "." or map[cur_y - 1][cur_x] == "B")
    ):
        seen[cur_y - 1][cur_x] = 1
        q.append(((cur_str + "U"), (cur_y - 1, cur_x)))
    # check left
    if (
        cur_x - 1 >= 0
        and seen[cur_y][cur_x - 1] == 0
        and (map[cur_y][cur_x - 1] == "." or map[cur_y][cur_x - 1] == "B")
    ):
        seen[cur_y][cur_x - 1] = 1
        q.append(((cur_str + "L"), (cur_y, cur_x - 1)))
    # check down
    if (
        cur_y + 1 < r
        and seen[cur_y + 1][cur_x] == 0
        and (map[cur_y + 1][cur_x] == "." or map[cur_y + 1][cur_x] == "B")
    ):
        seen[cur_y + 1][cur_x] = 1
        q.append(((cur_str + "D"), (cur_y + 1, cur_x)))
    # check right
    if (
        cur_x + 1 < c
        and seen[cur_y][cur_x + 1] == 0
        and (map[cur_y][cur_x + 1] == "." or map[cur_y][cur_x + 1] == "B")
    ):
        seen[cur_y][cur_x + 1] = 1
        q.append(((cur_str + "R"), (cur_y, cur_x + 1)))

print("NO")

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: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: TIME LIMIT EXCEEDED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED