Function dfs

python3/Graphs/count_islands.py:17–27

(r: int, c: int, matrix: List[List[int]])

    return count

def dfs(r: int, c: int, matrix: List[List[int]]) -> None:
    # Mark the current land cell as visited.
    matrix[r][c] = -1
    # Define direction vectors for up, down, left, and right.
    dirs = [(-1, 0), (1, 0), (0, -1), (0, 1)]
    # Recursively call DFS on each neighboring land cell to continue 
    # exploring this island.
    for d in dirs:
        next_r, next_c = r + d[0], c + d[1]
        if is_within_bounds(next_r, next_c, matrix) and matrix[next_r][next_c] == 1:
            dfs(next_r, next_c, matrix)

def is_within_bounds(r: int, c: int, matrix: List[List[int]]) -> bool:
    return 0 <= r < len(matrix) and 0 <= c < len(matrix[0])