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_114.java
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_114.java
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package com.fishercoder.solutions;
import com.fishercoder.common.classes.TreeNode;
public class _114 {
public static class Solution1 {
public void flatten(TreeNode root) {
while (root != null) {
if (root.left != null) {
TreeNode previousNode = root.left;
while (previousNode.right != null) {
previousNode = previousNode.right;
}
previousNode.right = root.right;
root.right = root.left;
root.left = null;
}
root = root.right;
}
}
}
public static class Solution2 {
/**
* Credit: https://leetcode.com/problems/flatten-binary-tree-to-linked-list/solution/
*/
public void flatten(TreeNode root) {
flat(root);
}
private TreeNode flat(TreeNode curr) {
if (curr == null) {
return null;
}
if (curr.left == null && curr.right == null) {
return curr;
}
TreeNode leftTail = flat(curr.left);
TreeNode rightTail = flat(curr.right);
if (leftTail != null) {
leftTail.right = curr.right;
curr.right = curr.left;
curr.left = null;
}
return rightTail == null ? leftTail : rightTail;
}
}
}