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ErChaSouSuoShuYuShuangXiangLianBiaoLcof.java
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ErChaSouSuoShuYuShuangXiangLianBiaoLcof.java
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package com.dbc;
import java.util.Stack;
public class ErChaSouSuoShuYuShuangXiangLianBiaoLcof {
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;
}
}
public Node treeToDoublyList(Node root) {
Stack<Node> stack = new Stack<>();
Node preNode = null, curNode = root, head = null;
while (!stack.isEmpty() || curNode != null) {
while (curNode != null) {
stack.add(curNode);
curNode = curNode.left;
}
curNode = stack.pop();
if (preNode == null) {
head = curNode;
} else {
preNode.right = curNode;
}
curNode.left = preNode;
preNode = curNode;
curNode = curNode.right;
}
if (head != null) {
head.left = preNode;
preNode.right = head;
}
return head;
}
}