// key-value 模型
public class HashBucket {
    private static class Node {
        private int key;
        private int value;
        Node next;
        public Node(int key, int value) {
            this.key = key;
            this.value = value;
        }
    }
    private Node[] array;
    private int size; // 当前的数据个数
    private static final double LOAD_FACTOR = 0.75;
    public int put(int key, int value) {
        int index = key % array.length;
// 在链表中查找 key 所在的结点
// 如果找到了，更新
// 所有结点都不是 key，插入一个新的结点
        for (Node cur = array[index]; cur != null; cur = cur.next) {
            if (key == cur.key) {
                int oldValue = cur.value;
                cur.value = value;
                return oldValue;
            }
        }
        Node node = new Node(key, value);
        node.next = array[index];
        array[index] = node;
        size++;
        if (loadFactor() >= LOAD_FACTOR) {    resize();    }
        return -1;
    }
    private void resize() {
        Node[] newArray = new Node[array.length * 2];
        for (int i = 0; i < array.length; i++) {
            Node next;
            for (Node cur = array[i]; cur != null; cur = next) {
                next = cur.next;
                int index = cur.key % newArray.length;
                cur.next = newArray[index];
                newArray[index] = cur;
            }
        }
        array = newArray;
    }
    private double loadFactor() {  return size * 1.0 / array.length;   }
    public HashBucket() {
        array = new Node[8];
        size = 0;
    }
    public int get(int key) {
        int index = key % array.length;
        Node head = array[index];
        for (Node cur = head; cur != null; cur = cur.next) {
            if (key == cur.key) {      return cur.value;    }
        }
        return -1;
    }
}