给你一棵二叉搜索树,请你 按中序遍历 将其重新排列为一棵递增顺序搜索树,使树中最左边的节点成为树的根节点,并且每个节点没有左子节点,只有一个右子节点。
示例
示例 1:
输入:root = [5,3,6,2,4,null,8,1,null,null,null,7,9]
输出:[1,null,2,null,3,null,4,null,5,null,6,null,7,null,8,null,9]
示例 2:
输入:root = [5,1,7]
输出:[1,null,5,null,7]
题解
中序遍历二叉树,储存每个节点,遍历节点将它们连接
/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @return {TreeNode}
*/
var increasingBST = function(root) {
const stack = []
const run = node => {
if (node.left) {
run(node.left)
}
stack.push(node)
if (node.right) {
run(node.right)
}
}
run(root)
const tree = stack[0]
tree.left = null
for (let i = 1; i < stack.length; i++) {
stack[i].left = null
stack[i - 1].right = stack[i]
}
return tree
};
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/increasing-order-search-tree
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