379. Design Phone Directory

Design a Phone Directory which supports the following operations:

 

1. get: Provide a number which is not assigned to anyone.
2. check: Check if a number is available or not.
3. release: Recycle or release a number.

 

Example:

// Init a phone directory containing a total of 3 numbers: 0, 1, and 2.
PhoneDirectory directory = new PhoneDirectory(3);

// It can return any available phone number. Here we assume it returns 0.
directory.get();

// Assume it returns 1.
directory.get();

// The number 2 is available, so return true.
directory.check(2);

// It returns 2, the only number that is left.
directory.get();

// The number 2 is no longer available, so return false.
directory.check(2);

// Release number 2 back to the pool.
directory.release(2);

// Number 2 is available again, return true.
directory.check(2);

 

 

---

 

class PhoneDirectory {
public:
    /** Initialize your data structure here
        @param maxNumbers - The maximum numbers that can be stored in the phone directory. */
    PhoneDirectory(int maxNumbers) {
        N = maxNumbers;
        for(int i = 0;i<N;i++) nums.push_back(i);
        assigned = vector<bool>(N,false);
    }
    
    /** Provide a number which is not assigned to anyone.
        @return - Return an available number. Return -1 if none is available. */
    int get() {
         for(int i = 0;i<N;i++)
         {
             if(!assigned[i]) 
             { 
                 assigned[i]= true;
                 return i;
             }
         }
         return -1;
    }
    
    /** Check if a number is available or not. */
    bool check(int number) {
         return !assigned[number];
    }
    
    /** Recycle or release a number. */
    void release(int number) {
        assigned[number]=false;
    }
private:
    vector<int> nums;
    vector<bool> assigned;
    int N;
};

/**
 * Your PhoneDirectory object will be instantiated and called as such:
 * PhoneDirectory obj = new PhoneDirectory(maxNumbers);
 * int param_1 = obj.get();
 * bool param_2 = obj.check(number);
 * obj.release(number);
 */