Leetcode 705 - Design HashSet

Note:

  • Use key % MOD to get the index.
  • To avoid hash collision, still need to check every e in set[key % MOD].

Question:

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

Implement MyHashSet class:

  • void add(key) Inserts the value key into the HashSet.
  • bool contains(key) Returns whether the value key exists in the HashSet or not.
  • void remove(key) Removes the value key in the HashSet. If key does not exist in the HashSet, do nothing.

Example:

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Input
["MyHashSet", "add", "add", "contains", "contains", "add", "contains", "remove", "contains"]
[[], [1], [2], [1], [3], [2], [2], [2], [2]]
Output
[null, null, null, true, false, null, true, null, false]

Explanation
MyHashSet myHashSet = new MyHashSet();
myHashSet.add(1); // set = [1]
myHashSet.add(2); // set = [1, 2]
myHashSet.contains(1); // return True
myHashSet.contains(3); // return False, (not found)
myHashSet.add(2); // set = [1, 2]
myHashSet.contains(2); // return True
myHashSet.remove(2); // set = [1]
myHashSet.contains(2); // return False, (already removed)

Code:

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

/**
* @param {number} key
* @return {void}
*/
MyHashSet.prototype.add = function(key) {
const index = key % this.BASE;
if (this.contains(key)) return;
this.hashSet[index].push(key);
};

/**
* @param {number} key
* @return {void}
*/
MyHashSet.prototype.remove = function(key) {
const index = key % this.BASE;
for (let i = 0; i < this.hashSet[index].length; i++) {
if (this.hashSet[index][i] === key){
this.hashSet[index].splice(i, 1);
return;
}
}
};

/**
* @param {number} key
* @return {boolean}
*/
MyHashSet.prototype.contains = function(key) {
const index = key % this.BASE;
for (let i = 0; i < this.hashSet[index].length; i++) {
if (this.hashSet[index][i] === key) return true;
}
return false;
};

/**
* Your MyHashSet object will be instantiated and called as such:
* var obj = new MyHashSet()
* obj.add(key)
* obj.remove(key)
* var param_3 = obj.contains(key)
*/