Abandoned warehouse

floor = "."
wall = "#"
Uolevi = "A"
exit = "B"


directions = [(-1, 0, 'U'), (1, 0, 'D'), (0, -1, 'L'), (0, 1, 'R')]

def function(n, m, warehouse):
    start = []
    end = []
    for i in range(n):
        for j in range(m):
            if warehouse[i][j] == Uolevi:
                start = (i, j)
            if warehouse[i][j] == exit:
                end = (i, j)
    if start == [] or end == []:
        print("NO")
        return None

    # BFS using list as queue
    queue = [start]
    # set up map
    visited = [[False]*m for _ in range(n)]
    # set starting point
    visited[start[0]][start[1]] = True

    parent = [[None]*m for _ in range(n)]
    
    head = 0  # index for the current element in queue
    while head < len(queue):
        x, y = queue[head]
        head += 1
        
        if (x, y) == end:
            # Reconstruct path
            path = []
            while (x, y) != start:
                px, py, move = parent[x][y]
                path.append(move)
                x, y = px, py
            path.reverse()

            return path
        
        for dx, dy, move in directions:
            nx, ny = x + dx, y + dy
            if 0 <= nx < n and 0 <= ny < m and not visited[nx][ny] and warehouse[nx][ny] != wall:
                visited[nx][ny] = True
                parent[nx][ny] = (x, y, move)
                queue.append((nx, ny))
    


def main():

    n, m = map(int, input().split())
    warehouse = []
    for i in range(n):
        warehouse.append(list(input()))
    
    result = function(n, m, warehouse)
    if result:
        print("YES")
        print(len(result))
        for i in result:
            print(i, end="")

    else:
        print("NO")
    return






if __name__ == "__main__":
    main()

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: TIME LIMIT EXCEEDED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: TIME LIMIT EXCEEDED