Leetcode 706 - Design HashMap

Note:

  • Very similar to Leetcode705, use mod to find the index, but this time it contains pairs like [key, value].

Question:

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

Implement the MyHashMap class:

  • MyHashMap() initializes the object with an empty map.
  • void put(int key, int value) inserts a (key, value) pair into the HashMap. If the key already exists in the map, update the corresponding value.
  • int get(int key) returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key.
  • void remove(key) removes the key and its corresponding value if the map contains the mapping for the key.

Example:

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Input
["MyHashMap", "put", "put", "get", "get", "put", "get", "remove", "get"]
[[], [1, 1], [2, 2], [1], [3], [2, 1], [2], [2], [2]]
Output
[null, null, null, 1, -1, null, 1, null, -1]

Explanation
MyHashMap myHashMap = new MyHashMap();
myHashMap.put(1, 1); // The map is now [[1,1]]
myHashMap.put(2, 2); // The map is now [[1,1], [2,2]]
myHashMap.get(1); // return 1, The map is now [[1,1], [2,2]]
myHashMap.get(3); // return -1 (i.e., not found), The map is now [[1,1], [2,2]]
myHashMap.put(2, 1); // The map is now [[1,1], [2,1]] (i.e., update the existing value)
myHashMap.get(2); // return 1, The map is now [[1,1], [2,1]]
myHashMap.remove(2); // remove the mapping for 2, The map is now [[1,1]]
myHashMap.get(2); // return -1 (i.e., not found), The map is now [[1,1]]

Code:

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var MyHashMap = function() {
this.BASE = 769;
this.map = [...new Array(769)].map(e => []);
};

/**
* @param {number} key
* @param {number} value
* @return {void}
*/
MyHashMap.prototype.put = function(key, value) {
const index = key % this.BASE;
// k,v inside `pair` are passed by reference.
for (const pair of this.map[index]) {
if (pair[0] === key) {
pair[1] = value;
return;
}
}
this.map[index].push([key, value]);
};

/**
* @param {number} key
* @return {number}
*/
MyHashMap.prototype.get = function(key) {
const index = key % this.BASE;
if (this.map[index].length === 0) return -1;
for (const [k, v] of this.map[index]) {
if (k === key) return v;
}
return -1;
};

/**
* @param {number} key
* @return {void}
*/
MyHashMap.prototype.remove = function(key) {
const index = key % this.BASE;
for (const [i, [k, v]] of this.map[index].entries()) {
if (k === key) {
this.map[index].splice(i, 1);
return;
}
}
};

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