import java.util.Queue;
import java.util.LinkedList;

public class BinaryTree<T extends Comparable<T>> {
	public Node root;

	BinaryTree(){
		root = null;
	}

	/*
	 *          10
	 *     5          15
	 *  3     7    12    20
	 *
	 * preOrder: 10 5 3 7 15 12 20
	 */
	public void preOrderTraversal(){
		preOrder(root);
	}
	public void preOrder(Node tree){
		if(tree != null ){
			System.out.print(tree.value);
			System.out.print(" ");
			preOrder(tree.left);
			preOrder(tree.right);
		}
	}

	public void inOrder(){}
	public void postOrder(){}
	public void levelOrder(){}

	public void insert(T val){
		Node<T> newNode = new Node(val);
		Node<T> temp = root;

		if(root == null){
			root = newNode;
			return;
		}

		while(temp != null){
			if(val.compareTo(temp.value) < 0){
				if(temp.left != null){
					temp = temp.left;
				} else {
					temp.left = newNode;
					break;
				}
			} else if(val.compareTo(temp.value) == 0){
				break;
			}
			else {
				if(temp.right != null){
					temp = temp.right;
				} else {
					temp.right = newNode;
					break;
				}
			}
		}

	}

	public void delete(T val){
		if(root == null){
			return;
		}
		// 1. 找到被删的节点及其父节点
		Node<T> parent = root;
		Node<T> current = root;
		while(current != null){
			if(val.compareTo(current.value) == 0){
				break;
			} else if(val.compareTo(current.value) < 0){
				parent = current;
				current = current.left;
			} else {
				parent = current;
				current = current.right;
			}
		}

		// while结束后：1. 找到了 current !=null 2. 没找到 current == null
		// 2. 删除3种情况
		if(current != null){
			// 2.1 leaf, 0 child
			if(current.left == null && current.right == null){
				if(current == root){
					root = null;
				} else {
					if(parent.left == current){
						parent.left = null;
					} else {
						parent.right = null;
					}
				}				
			}
			// 2.2 1 child
			else if (current.left == null || current.right == null){
				
			}
			// 2.3 2 children
			else {
				T maxValue = findMaxAndDelete(current, current.left);
				current.value = maxValue;				
			}
		}
	}


	private T findMaxAndDelete(Node beReplaced, Node root){
		Node<T> parent = beReplaced;
		Node<T> current = root;
		while(current != null && current.right != null){
			parent = current;
			current = current.right;
		}

		// while结束后, current是当前root树的最大值
		if(current.left != null){
			if(parent.left == current){
				parent.left = current.left;
			} else {
				parent.right = current.left;
			}
		} else {
			parent.right = null;
		}
		return current.value;
	}

}