LeetCode-705. Design HashSet

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问题描述

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)

Constraints:

  • 0 <= key <= 106
  • At most 104 calls will be made to add, remove, and contains.

解答

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/*
 * @Description: 705. Design HashSet
 * @Author: libk
 * @Github: https://github.com/libk
 */
/**
 * 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)
 */
const MyHashSet = function () {
  this.BASE = 769
  this.data = new Array(this.BASE).fill(0).map(() => [])
}

/**
 * @param {number} key
 * @return {void}
 */
MyHashSet.prototype.add = function (key) {
  let index = this.hash(key)
  let node = this.data[index]
  for (let i = 0; i < node.length; i++) {
    if (node[i] === key) {
      return
    }
  }
  node.push(key)
}

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

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

/**
 * @param {number} key
 * @return {number}
 */
MyHashSet.prototype.hash = function (key) {
  return key % this.BASE
}