705.design-hash-set.cpp

/*
 * @lc app=leetcode id=705 lang=cpp
 *
 * [705] Design HashSet
 *
 * https://leetcode.com/problems/design-hashset/description/
 *
 * algorithms
 * Easy (66.08%)
 * Likes:    2268
 * Dislikes: 218
 * Total Accepted:    249.3K
 * Total Submissions: 377.4K
 * Testcase Example:  '["MyHashSet","add","add","contains","contains","add","contains","remove","contains"]\n' +
  '[[],[1],[2],[1],[3],[2],[2],[2],[2]]'
 *
 * 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 1:
 *
 *
 * 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 <= 10^6
 * At most 10^4 calls will be made to add, remove, and contains.
 *
 *
 */

// @lc code=start
class MyHashSet
{
private:
    vector<bool> *set;

public:
    MyHashSet() : set(new vector<bool>(1000001, false)) {}
    void add(int key) { (*set)[key] = true; }
    void remove(int key) { (*set)[key] = false; }
    bool contains(int key) { return (*set)[key]; }
};

/**
 * Your MyHashSet object will be instantiated and called as such:
 * MyHashSet* obj = new MyHashSet();
 * obj->add(key);
 * obj->remove(key);
 * bool param_3 = obj->contains(key);
 */
// @lc code=end