每日一道Leetcode - 897. 递增顺序查找树 【中序遍历】

简单的思路就是，中序遍历存储每个节点于数组中，再遍历数组，构建新的树，右子树，一直遍历下去。

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    
    
    public TreeNode increasingBST(TreeNode root) {
    
    
        List<Integer> vals = new ArrayList();
        inorder(root,vals);
        TreeNode res = new TreeNode(0);
        TreeNode p = res;
        for(int v:vals){
    
    
            p.right = new TreeNode(v);
            p = p.right;
        }
        return res.right;
    }
    public void inorder(TreeNode node, List<Integer> vals){
    
    
        if(node == null) return;
        inorder(node.left,vals);
        vals.add(node.val);
        inorder(node.right,vals);
    }
}