排序去重

场景：对数组进行排序和去重

java 8 stream实现

List<String> list = Arrays.asList("EE", "AA","AA","BB");
list.stream()
        .distinct()
        .sorted()
        .forEach(x -> System.out.println(x));

二叉树实现

思路： 根据数组构造一棵有序的二叉树，其中如果相等的元素忽略(去除掉)

import java.util.ArrayList;
import java.util.List;

public class BinaryTree<T extends Comparable> {
    class Node {
        private Node left;
        private Node right;
        private T data;
        private boolean distinct;

        public Node(T data, boolean distinct){
            this.data = data;
            this.distinct = distinct;
        }

        public void addNode(Node newNode) {
            int compare = newNode.data.compareTo(this.data);

            //put smaller on the left node
            if (compare < 0) {
                if (this.left == null) {
                    this.left = newNode;
                } else {
                    this.left.addNode(newNode);
                }

                return;
            }

            //put bigger on the right node
            if (compare > 0 || !this.distinct) {
                if (this.right == null) {
                    this.right = newNode;
                } else {
                    this.right.addNode(newNode);
                }

                return;
            }
        }

        public void toList(List<T> list){
            if (this.left != null) {
                this.left.toList(list);
            }

            list.add(this.data);

            if (this.right != null) {
                this.right.toList(list);
            }
        }
    }

    private Node root;
    private boolean distinct;

    public BinaryTree() {
        this.distinct = false;
    }

    public BinaryTree(boolean distinct) {
        this.distinct = distinct;
    }

    public List<T> sort(Iterable<T> iterable) {
        for (T data : iterable){
            Node newNode = new Node(data, this.distinct);
            if (this.root == null) {
                this.root = newNode;
            } else {
                this.root.addNode(newNode);
            }
        }
        List<T> result = new ArrayList<>();
        if (this.root == null) {
            return result;
        }

        this.root.toList(result);
        return result;
    }

    public static void main(String[] args){
        List<String> list = Arrays.asList("EE", "BB", "AA","AA","BB");
        BinaryTree<String> bt = new BinaryTree(true);
        List<String> result = bt.sort(list);
        for (String k : result){
            System.out.println(k);
        }
    }
}