Saturday, August 1, 2020

705. Design HashSet -----------E

Q:

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

To be specific, your design should include these functions:

  • add(value): Insert a value into the HashSet. 
  • contains(value) : Return whether the value exists in the HashSet or not.
  • remove(value): Remove a value in the HashSet. If the value does not exist in the HashSet, do nothing.


Example:

MyHashSet hashSet = new MyHashSet();
hashSet.add(1);         
hashSet.add(2);         
hashSet.contains(1);    // returns true
hashSet.contains(3);    // returns false (not found)
hashSet.add(2);          
hashSet.contains(2);    // returns true
hashSet.remove(2);          
hashSet.contains(2);    // returns false (already removed)


Note:

  • All 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 HashSet library.
A:
class MyHashSet {
public:
    /** Initialize your data structure here. */
    MyHashSet() {
        SS = vector<bool>(1000001,false);
    }
    
    void add(int key) {
        SS[key]=true;
    }
    
    void remove(int key) {
        SS[key] = false;
    }
    
    /** Returns true if this set contains the specified element */
    bool contains(int key) {
        return SS[key];
    }
private:    
    vector<bool> SS;
};

/**
 * 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);
 */

Mistakes:
 error: expected parameter declarator
vector<bool> SS<100000,false>;
需要在constructor里生成

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