使用BST的Java递归

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;

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

public class BinarySearchTree {
    private TreeNode root;

    public BinarySearchTree() {
        root = null;
    }

    // 插入节点
    public void insert(int val) {
        root = insertRec(root, val);
    }

    private TreeNode insertRec(TreeNode root, int val) {
        if (root == null) {
            root = new TreeNode(val);
            return root;
        }

        if (val < root.val) {
            root.left = insertRec(root.left, val);
        } else if (val > root.val) {
            root.right = insertRec(root.right, val);
        }

        return root;
    }

    // 查找节点
    public boolean search(int val) {
        return searchRec(root, val);
    }

    private boolean searchRec(TreeNode root, int val) {
        if (root == null) {
            return false;
        }

        if (root.val == val) {
            return true;
        }

        if (val < root.val) {
            return searchRec(root.left, val);
        } else {
            return searchRec(root.right, val);
        }
    }
}