706. Design HashMap (Easy)

https://leetcode.com/problems/design-hashmap/

Design a HashMap without using any built-in hash table libraries.

To be specific, your design should include these functions:

  • put(key, value) : Insert a (key, value) pair into the HashMap. If the value already exists in the HashMap, update the value.
  • get(key): Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key.
  • remove(key) : Remove the mapping for the value key if this map contains the mapping for the key.


Example:

MyHashMap hashMap = new MyHashMap();
hashMap.put(1, 1);          
hashMap.put(2, 2);         
hashMap.get(1);            // returns 1
hashMap.get(3);            // returns -1 (not found)
hashMap.put(2, 1);          // update the existing value
hashMap.get(2);            // returns 1 
hashMap.remove(2);          // remove the mapping for 2
hashMap.get(2);            // returns -1 (not found) 


Note:

  • All keys and values will be in the range of [0, 1000000].
  • The number of operations will be in the range of [1, 10000].
  • Please do not use the built-in HashMap library.

Solutions

class MyHashMap {
    int[] map;

    public MyHashMap() {
        map = new int[1000001];
        Arrays.fill(map, -1);
    }

    public void put(int key, int value) {
        map[key] = value;
    }

    public int get(int key) {
        return map[key];
    }

    public void remove(int key) {
        map[key] = -1;
    }
}

Incorrect Solutions

References

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