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package g0001_0100.s0099_recover_binary_search_tree;
// #Medium #Depth_First_Search #Tree #Binary_Tree #Binary_Search_Tree
// #2022_06_21_Time_3_ms_(76.33%)_Space_47.3_MB_(52.92%)
import com_github_leetcode.TreeNode;
/*
* 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;
* }
* }
*/
public class Solution {
private TreeNode prev = null;
private TreeNode first = null;
private TreeNode second = null;
public void recoverTree(TreeNode root) {
evalSwappedNodes(root);
int temp = first.val;
first.val = second.val;
second.val = temp;
}
private void evalSwappedNodes(TreeNode curr) {
if (curr == null) {
return;
}
evalSwappedNodes(curr.left);
if (prev != null && prev.val > curr.val) {
if (first == null) {
first = prev;
}
second = curr;
}
prev = curr;
evalSwappedNodes(curr.right);
}
}