Binary search tree java achieve

Binary search tree

1. Definitions

1. If the left subtree is not empty, then the value of the left sub-tree, all the nodes are less than the value of its root
2. If the right subtree is not empty, then the right sub-tree nodes are all values ​​greater than the value of its root
3. Left and right subtrees are also binary search tree
4. It does not equal node key

2. deletions check

2.1 Inserting

 public void insert(T val) {
    if (val == null)
        throw new NullPointerException();
    root = insert(val, root);
}

/**
 * 插入方法的实际执行
 */
private Node<T> insert(T val, Node<T> t) {
    if (root == null) {
        return new Node<>(val, null, null);
    }
    int compareRes = val.compareTo(root.value);
    if (compareRes > 0) {
        root.right = insert(val, root.right);
    } else if (compareRes < 0) {
        root.left = insert(val, root.left);
    }
    return t;
}

Find 2.2

Find the tree contains this value

/**
 * 查看二叉树中是否包含此值
 */
public boolean contains(T val) {
    if (val == null) {
        throw new NullPointerException();
    }
    return contains(val, root);
}
private boolean contains(T val, Node<T> t) {
    if (t == null) {
        return false;
    }
    int compareRes = val.compareTo(t.value);
    if (compareRes > 0) {
        return contains(val, t.right);
    } else if (compareRes < 0) {
        return contains(val, t.left);
    } else {
        return true;
    }
}

Find the maximum value of 2.3

/**
 * 获取最大值
 */
public T findMax() {
    if (root == null) {
        return null;
    }
    return findMax(root).value;
}
private Node<T> findMax(Node<T> t) {
    while (t.right != null)
        t = t.right;
    return t;

Find the minimum value of 2.4

/**
 * 获取最小值
 */
public T findMin() {
    if (root == null) {
        return null;
    }
    return findMin(root).value;
}
private Node<T> findMin(Node<T> t) {
    while (t.left != null) {
        t = t.left;
    }
    return t;
}

2.5 Delete

public Node<T> delete(T val) {
    if (val == null)
        throw new NullPointerException();
    return delete(val, root);
}
private Node<T> delete(T val, Node<T> t) {
    if (t == null)
        return null;
    int compareRes = val.compareTo(t.value);
    if (compareRes > 0)
        delete(val, t.right);
    else if (compareRes < 0)
        delete(val, t.left);
    else if (t.left != null && t.right != null) {
        Node<T> temp = findMin(t.right);
        t.value = temp.value;
        delete(val,temp);
    }else
        t = (t.left ==null ? t.right:t.left);
    return t;
}