NYOJ：94cigarettes

cigarettes

描述

Tom has many cigarettes. We hypothesized that he has n cigarettes and smokes them

one by one keeping all the butts. Out of k > 1 butts he can roll a new cigarette. 
Now，do you know how many cigarettes can Tom has?

输入

First input is a single line,it's n and stands for there are n testdata.then there are n lines ,each line contains two integer numbers giving the values of n and k.

输出

For each line of input, output one integer number on a separate line giving the maximum number of cigarettes that Peter can have.

样例输入

3
4 3
10 3
100 5

样例输出

5
14
124

a是香烟数，b意思是吸b根他就卷一根，求的是他将所有烟吸完，他总共吸了多少根烟。进入循环后，a为当前剩余香烟数，sum是他已经吸了的香烟数，如果a<b,则他把这a根吸完了，下一根还没卷出，他已经吸完了所有的香烟。

#include<stdio.h>

int main()

{

 int num,a,b,sum;

scanf("%d",&num);

  while(num--)
 {      
        sum=0;
        scanf("%d%d",&a,&b);
        while(a>=b)
        {
            a=a-b;
            sum=sum+b;
            a=a+1;
        }
        printf("%d\n",sum+a);
    }
    return 0;
}