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InvertBinaryTree.java
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InvertBinaryTree.java
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package Leetcode;
import java.util.Deque;
import java.util.LinkedList;
/**
* @author kalpak
*
* Invert a binary tree.
*
* Example:
*
* Input:
*
* 4
* / \
* 2 7
* / \ / \
* 1 3 6 9
* Output:
*
* 4
* / \
* 7 2
* / \ / \
* 9 6 3 1
*
*/
public class InvertBinaryTree {
public static TreeNode invertTreeDFS(TreeNode root) {
if(root == null)
return null;
TreeNode tempLeft = root.left;
root.left = invertTreeDFS(root.right);
root.right = invertTreeDFS(tempLeft);
return root;
}
public static TreeNode invertTreeBFS(TreeNode root) {
Deque<TreeNode> queue = new LinkedList<>();
if(root == null)
return null;
queue.offer(root);
while(!queue.isEmpty()) {
TreeNode current = queue.poll();
TreeNode tempLeft = current.left;
current.left = current.right;
current.right = tempLeft;
if(current.left != null)
queue.offer(current.left);
if(current.right != null)
queue.offer(current.right);
}
return root;
}
public static void main(String[] args) {
TreeNode root = new TreeNode(12);
root.left = new TreeNode(7);
root.right = new TreeNode(1);
root.left.left = new TreeNode(9);
root.right.left = new TreeNode(10);
root.right.right = new TreeNode(5);
TreeNode result = invertTreeDFS(root);
}
}