Find which numbers appears most in a vector

Question

I have some numbers stored in a vector . I want to find which number appears most in the vector.

Is there any easy/fast algorithm (STL or whatever) that does this ?<

Answer 1

You can use the following code:

vector  v;
    // add some elements
    v.push_back(1);
    v.push_back(2);
    v.push_back(3);
    v.push_back(1);

    int maxCount = 0, mostElement = *(v.begin());
    int sz = v.size(); // to avoid calculating the size every time
    for(int i=0; i < sz; i++)
    {
        int c = count(v.begin(), v.end(), v.at(i));
        if(c > maxCount)
        {   maxCount = c;
            mostElement = v.at(i);
        }
    }
    cout << "the number appeared the most is " << mostElement <<"\n";
    cout << "it appered " <

note: you can use the following for loop to avoid any iterator overflow if the size of the vector can't be held by an integer:

    for(auto it= v.begin(); it != v.end(); it++)
    {
        int c = count(v.begin(), v.end(), *it);
        if(c > maxCount)
        {   maxCount = c;
            mostElement = *it;
        }
    }