LeetCode: Flatten Binary Tree to Linked List

LeetCode: Flatten Binary Tree to Linked List

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/**
* Description
*
* @author hzhou
*/
public class FlattenBinaryTreeToLinkedList {
public void flatten(TreeNode root) {
if (root == null) {
return;
}
Stack<TreeNode> stack = new Stack<TreeNode>();
TreeNode cursor = new TreeNode(0);
stack.push(root);
while (!stack.isEmpty()) {
cursor.right = stack.pop();
cursor.left = null;
cursor = cursor.right;
if (cursor.right != null) {
stack.push(cursor.right);
}
if (cursor.left != null) {
cursor.right = cursor.left;
if (cursor.left.right != null) {
stack.push(cursor.left.right);
}
if (cursor.left.left != null) {
stack.push(cursor.left.left);
}
cursor.left = null;
cursor = cursor.right;
}
}
}
@Test
public void test() {
TreeNode root = new TreeNode(1);
root.left = new TreeNode(2);
/*root.right = new TreeNode(5);
root.left.left = new TreeNode(3);
root.left.right = new TreeNode(4);
root.right.right = new TreeNode(6);
*/
flatten(root);
}
}