二叉树-如何删除元素；java

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    
    public TreeNode(int val) {
        this.val = val;
        this.left = null;
        this.right = null;
    }
}

class BinaryTree {
    private TreeNode root;
    
    public BinaryTree() {
        this.root = null;
    }
    
    // 删除元素
    public void delete(int val) {
        root = deleteNode(root, val);
    }
    
    private TreeNode deleteNode(TreeNode root, int val) {
        if (root == null) {
            return null;
        }
        
        if (val < root.val) {
            root.left = deleteNode(root.left, val);
        } else if (val > root.val) {
            root.right = deleteNode(root.right, val);
        } else {
            // 找到要删除的节点
            if (root.left == null) {
                return root.right;
            } else if (root.right == null) {
                return root.left;
            }
            
            // 有两个子节点的情况
            TreeNode minNode = findMin(root.right);
            root.val = minNode.val;
            root.right = deleteNode(root.right, minNode.val);
        }
        
        return root;
    }
    
    private TreeNode findMin(TreeNode node) {
        while (node.left != null) {
            node = node.left;
        }
        return node;
    }
}