how to derive New Year Candles formula

Revision en3, by piyushgoyal443, 2016-08-31 04:13:02

this is my solution and it works


#include < iostream >

using namespace std;

int main()
{
    int a, b, div, rem;
    cin >> a >> b;
    int sum = a;
    while(a >= b)
    {
        div = a / b;
        sum += div;
        rem = a % b;
        a = div + rem;
    }
    cout << sum << endl;
    return 0;
}

[link to the problem] (http://codeforces.com/problemset/problem/379/A)
`

but I saw other people solutions and they have used a formula that calculates answer without any loop

 ans = (a * b — 1)/(b — 1) 

Can someone please help me how to get this formula?

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  Rev. Lang. By When Δ Comment
en3 English piyushgoyal443 2016-08-31 04:13:02 78
en2 English piyushgoyal443 2016-08-30 17:47:44 58 Tiny change: 'codeio' -
en1 English piyushgoyal443 2016-08-30 17:35:19 563 Initial revision (published)