LeetCode 897 Increasing Order Search Tree
摘要：
給定一顆二叉搜尋樹，重新進行排序，使其根節點是最小值，且每個節點都沒有左子樹，只有一個右子樹，最終還要保持該樹是一顆二叉搜尋樹.
例 1:
給予樹:
5
/ \
36
/ \\
248
/...
給定一顆二叉搜尋樹，重新進行排序，使其根節點是最小值，且每個節點都沒有左子樹，只有一個右子樹，最終還要保持該樹是一顆二叉搜尋樹.
例 1: 給予樹: 5 / \ 36 / \\ 248 // \ 179 輸出: 1 \ 2 \ 3 \ 4 \ 5 \ 6 \ 7 \ 8 \ 9
解法
使用中序遍歷即可。
/**
* Definition for a binary tree node.
* public class TreeNode {
*int val;
*TreeNode left;
*TreeNode right;
*TreeNode(int x) { val = x; }
* }
*/
class Solution {
private TreeNode result = new TreeNode(0);
private TreeNode dummy = result;
public TreeNode increasingBST(TreeNode root) {
if (root == null) {
return null;
}
increasingBST(root.left);
dummy.right = new TreeNode(root.val);
dummy = dummy.right;
increasingBST(root.right);
return result.right;
}
}
Runtime: 2 ms, faster than 99.97% of Java online submissions for Increasing Order Search Tree. Memory Usage: 44.9 MB, less than 59.39% of Java online submissions for Increasing Order Search Tree.