99. 恢复二叉搜索树

99. 恢复二叉搜索树

My Solution

利用二叉树中序遍历有序的性质恢复

/**
 * 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 {
    List<Integer> list = new ArrayList<>();
    int index = 0;
    public void recoverTree(TreeNode root) {
        visit(root);
        Collections.sort(list);
        print(root);
    }
    public void visit(TreeNode root) {
        if (root == null) {
            return;
        }
        visit(root.left);
        list.add(root.val);
        visit(root.right);
    }
    public void print(TreeNode root) {
        if (root == null) {
            return ;
        }
        print(root.left);
        root.val = list.get(index++);
        print(root.right);
    }
}