> For the complete documentation index, see [llms.txt](https://docs.1l.lol/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.1l.lol/data-structures/tree-storage.md).

# 树的存储方式

### 双亲表示法

每个结点记录其父结点下标，适合找父亲：

```cpp
int parent[N];   // parent[i] = i 的父亲
```

### 孩子表示法

每个结点存一个孩子链表 / 数组，适合找孩子。

### 孩子兄弟表示法

每个结点存「第一个孩子」和「下一个兄弟」两个指针，可把任意树转成二叉树：

```cpp
struct Node { int child, sibling; };
```

### 邻接表存储树

树是无环连通图，用邻接表存最通用：

```cpp
vector<int> adj[N];
for (int i = 1; i < n; i++) {
    int u, v; cin >> u >> v;
    adj[u].push_back(v);
    adj[v].push_back(u);
}
```

### 对比

| 表示法  | 擅长       |
| ---- | -------- |
| 双亲   | 找父亲、自底向上 |
| 孩子   | 找孩子、自顶向下 |
| 孩子兄弟 | 树转二叉树    |
| 邻接表  | 遍历、通用算法  |


---

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