Insert node to BST
- 难度:简单
给定一棵二叉查找树和一个新的树节点,将节点插入到树中。
你需要保证该树仍然是一棵二叉查找树。
样例
给出如下一棵二叉查找树,在插入节点6之后这棵二叉查找树可以是这样的:
2 2
/ \ / \
1 4 --> 1 4
/ / \
3 3 6
挑战
能否不使用递归?
Solution
简单题,每个node决定是往左还是往右还是就是这个节点。类似二分的做法。
Code
/**
* Definition of TreeNode:
* public class TreeNode {
* public int val;
* public TreeNode left, right;
* public TreeNode(int val) {
* this.val = val;
* this.left = this.right = null;
* }
* }
*/
public class Solution {
/**
* @param root: The root of the binary search tree.
* @param node: insert this node into the binary search tree
* @return: The root of the new binary search tree.
*/
public TreeNode insertNode(TreeNode root, TreeNode node) {
if (root == null) {
root = node;
return root;
}
TreeNode tmp = root;
TreeNode last = null;
while (tmp != null) {
last = tmp;
if (tmp.val > node.val) {
tmp = tmp.left;
} else {
tmp = tmp.right;
}
}
if (last != null) {
if (last.val > node.val) {
last.left = node;
} else {
last.right = node;
}
}
return root;
}
}