897. 递增顺序查找树

 

 

 

/**
 * 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 ans = new TreeNode(0);
        TreeNode cur = ans;
        for(int v : vals) {
            cur.right = new TreeNode(v);
            cur = cur.right;
        }
        return ans.right;
    }

    public void InOrder(TreeNode root, List<Integer> vals) {
        if(root == null)    return ;
        InOrder(root.left, vals);
        vals.add(root.val);
        InOrder(root.right, vals);
    }
}