706. 设计哈希映射

不使用任何内建的哈希表库设计一个哈希映射（HashMap）。

实现MyHashMap 类：

MyHashMap() 用空映射初始化对象
void put(int key, int value) 向 HashMap 插入一个键值对 (key, value) 。如果 key 已经存在于映射中，则更新其对应的值 value 。
int get(int key)返回特定的 key 所映射的 value ；如果映射中不包含 key 的映射，返回 -1 。
void remove(key)如果映射中存在 key 的映射，则移除 key 和它所对应的 value 。

class MyHashMap {
    private class Pair {
        private int key;
        private int value;

        public Pair(int key, int value) {
            this.key = key;
            this.value = value;
        }

        public int getKey() {
            return key;
        }

        public int getValue() {
            return value;
        }

        public void setValue(int value) {
            this.value = value;
        }
    }

    private static final int BASE = 769;
    private LinkedList[] data;

    /** Initialize your data structure here. */
    public MyHashMap() {
        data = new LinkedList[BASE];
        for (int i = 0; i < BASE; ++i) {
            data[i] = new LinkedList<Pair>();
        }
    }
    
    /** value will always be non-negative. */
    public void put(int key, int value) {
        int h = hash(key);
        Iterator<Pair> iterator = data[h].iterator();
        while (iterator.hasNext()) {
            Pair pair = iterator.next();
            if (pair.getKey() == key) {
                pair.setValue(value);
                return;
            }
        }
        data[h].offerLast(new Pair(key, value));
    }
    
    /** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
    public int get(int key) {
        int h = hash(key);
        Iterator<Pair> iterator = data[h].iterator();
        while (iterator.hasNext()) {
            Pair pair = iterator.next();
            if (pair.getKey() == key) {
                return pair.value;
            }
        }
        return -1;
    }
    
    /** Removes the mapping of the specified value key if this map contains a mapping for the key */
    public void remove(int key) {
        int h = hash(key);
        Iterator<Pair> iterator = data[h].iterator();
        while (iterator.hasNext()) {
            Pair pair = iterator.next();
            if (pair.key == key) {
                data[h].remove(pair);
                return;
            }
        }
    }

    private static int hash(int key) {
        return key % BASE;
    }
}



/**
 * Your MyHashMap object will be instantiated and called as such:
 * MyHashMap obj = new MyHashMap();
 * obj.put(key,value);
 * int param_2 = obj.get(key);
 * obj.remove(key);
 */