from typing import List


def predecessor_map(cfg: List[List[int]]) -> List[List[int]]:
    """Returns a parallel list mapping each node to a list of its preds."""
    preds = [[] for _ in range(len(cfg))]
    for i in range(len(cfg)):
        for succ in cfg[i]:
            preds[succ].append(i)
    return preds