Question

假设你有这样的哈希：

{"a" => {
    "b" => {
        "d" => {}
    },
    "c" => {
        "e" => {},
        "f" => {
            "g" => {}
        }
    }
}

我想编写一个函数（使用递归），如果"a"是{{1}的直接后代，则为特定的一对键（例如"f"和"f"）返回true }}。树中两者之间的深度或距离无关紧要。所有其他实例（例如"a"是"a"的后代，或"f"和"a"位于不同的分支上）应返回"f"。

Answer 1

def are_descendants?(hash, node, target)
  node_hash = hash[node]

  # check
  # 1) the hash does actually have the node specified to be the start as a key 
  # 2) the target key is direct child => done 
  # 3) if not: check if any of the children is a parent of the target
  # 4) if the hash does not have the node specified to be the start, then look inside one of the hash's inner hashes
  (node_hash && 
    (node_hash.has_key?(target) || 
     node_hash.keys.any? { |key| are_descendants?(node_hash, key, target) })) ||
    hash.any? { |_, inner_hash| are_descendants?(inner_hash, node, target) })


end

are_descendants?(hash, "a", "f")
  => true

are_descendants?(hash, "f", "a")
  => false

are_descendants?(hash, "c", "f")
  => true

在Ruby中，如何遍历父子关系中两个节点的哈希树

1 个答案: