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Offer36.java
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Offer36.java
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package lcof;
/**
* Offer 36. 二叉搜索树与双向链表
* 二叉搜索树的中序遍历 & 链表
* @author LBW
*/
public class Offer36 {
Node head, pre;
public Node treeToDoublyList(Node root) {
if (root == null)
return null;
dfs(root);
// 头尾之间相连
head.left = pre;
pre.right = head;
return head;
}
private void dfs(Node cur) {
if (cur == null) {
return;
}
dfs(cur.left);
if (pre == null) { // 说明在访问链表的头节点
head = cur;
pre = cur;
}
else { // 将 pre 和 cur 之间做双向链表关联
pre.right = cur;
cur.left = pre;
// update pre
pre = cur;
}
dfs(cur.right);
}
static class Node {
public int val;
public Node left;
public Node right;
public Node() {}
public Node(int _val) {
val = _val;
}
public Node(int _val,Node _left,Node _right) {
val = _val;
left = _left;
right = _right;
}
};
}