二叉树之查询

二叉树的查询是建立遍历的基础上更进一步的对比查询，下面分别从前序、中序、后续三种方法中查询对应的节点。

前序查找

    /**
     * 前序查询
     */
    public Person preSelectById(Integer id) {
        Person person = null;
        if (this.data.getId().equals(id)) {
            person = this.data;
        }
        if (Objects.isNull(person) && Objects.nonNull(this.left)) {
            person = this.left.preSelectById(id);
        }
        if (Objects.isNull(person) && Objects.nonNull(this.right)) {
            person = this.right.preSelectById(id);
        }
        return person;
    }

中序查找

    /**
     * 中序查询
     */
    public Person midSelectById(Integer id) {
        Person person = null;
        if (Objects.isNull(person) && Objects.nonNull(this.left)) {
            person = this.left.preSelectById(id);
        }
        if (this.data.getId().equals(id)) {
            person = this.data;
        }
        if (Objects.isNull(person) && Objects.nonNull(this.right)) {
            person = this.right.preSelectById(id);
        }
        return person;
    }

后序查找

    /**
     * 后序查询
     */
    public Person postSelectById(Integer id) {
        Person person = null;
        if (Objects.isNull(person) && Objects.nonNull(this.left)) {
            person = this.left.preSelectById(id);
        }
        if (Objects.isNull(person) && Objects.nonNull(this.right)) {
            person = this.right.preSelectById(id);
        }
        if (this.data.getId().equals(id)) {
            person = this.data;
        }
        return person;
    }

源码与测试案例

gitee地址