public static void TreeTraversal()
{
//Define a binary tree.
// 1
// / \
// 2 3
// / \ / \
// 4 5 6 7
TreeNode root = new TreeNode(1);
root.left = new TreeNode(2);
root.right = new TreeNode(3);
root.left.left = new TreeNode(4);
root.left.right = new TreeNode(5);
root.right.left = new TreeNode(6);
root.right.right = new TreeNode(7);
List<string> TreePath = root.ListBinaryTreePath1(root);
List<string> TreePath2 = root.ListBinaryTreePath2(root);
List<int> preResult = root.PreOrderTraversal(root); //1, 2, 4, 5, 3, 6, 7
List<int> preResult_i = root.PreOrderTraversal_Iterative1(root);
List<int> preResult_i2 = root.PreOrderTraversal_Iterative2(root);
List<int> inResult = root.InOrderTraversal(root); //4, 2, 5, 1, 6, 3, 7
List<int> inResult_i = root.InOrderTraversal_Iterative1(root);
List<int> postResult = root.PostOrderTraversal(root); //4, 5, 2, 6, 7, 3, 1
List<int> postResult_i = root.PostOrderTraversal_Iterative1(root);
List<int> postResult_i2 = root.PostOrderTraversal_Iterative2(root);
List<List<int>> levelResult = root.LevelOrderTraversal(root);
}
