Question

Problem Statement

In a restaurant, if you were pleased by the waiter's service, you may leave him a tip -- you pay him more than the actual value of the bill, and the waiter keeps the excess money. In some countries, not leaving a tip for the waiter is even considered impolite. During my recent holiday I was having dinner in a foreign restaurant. The pamphlet from my travel agency informed me that the proper way of tipping the waiter is the following:

• The sum I pay must be round, i.e., divisible by 5.
• The tip must be between 5% and 10% of the final sum I pay, inclusive.

Clearly, sometimes there may be multiple "correct" ways of settling the bill. I'd like to know exactly how many choices I have in a given situation. I could program it easily, but I was having a holiday... and so it's you who has to solve this task. You will be given:

• an int bill -- the amount I have to pay for the dinner
• an int cash -- the amount of money I have in my pocket

Write a function that computes how many different final sums satisfy the conditions above.

Constraints

1. Assume that both bill and cash are in dollars.
2. All the money I have is in one-dollar banknotes.

Examples

1. 4  100
   
   Returns:  0
   

   4 isn't a round sum, and 5 is too much.

2. 23  100
   
   Returns: 1
   

   The only correct choice is to pay 25 dollars, thus leaving a tip of 2 dollars.

3. 23  24
   
   Returns: 0
   

   The same bill, but I don't have enough money to leave an appropriate tip.

4. 220  239
   
   Returns: 1
   

   This time, it is appropriate to pay either 235 or 240 dollars. Sadly, I don't have enough money for the second possibility.

5. 1234567  12345678
   
   Returns: 14440
   

   A large bill, but with that much money I don't care.

6. 1880000000  1980000000
   
   Returns: 210527
   

7. 171000000  179999999
   
   Returns: 0

Given Function

int possible_payments(int bill, int cash) {
// fill in code here
}

Answer the problem statement by completing the Given Function. Follow the constraints and examples.

Answer 1

The code is written in C if you want you can also compile it in c++ using the required headers. Comments are included in the code. If you require any clarifications please ask in the comments. Thank you.  

Note: Go through the code screenshot to understand the indentation in a better way.

THE CODE:

#include<stdio.h>

#include<stdlib.h>

//Function to calculate the number of ways

long int possible_payments(long int bill, long int cash) {

   //Calculate the number to remaining to get to the nearest multiple of 5

   int rem = (5-bill%5);

   bill+=rem;

   //Varibale to calaculate the tip

   long int tip = rem;

   //Varible to store the number of ways

   long int ways = 0;

   double percentage = 0.0;

   //This loops till the amount of bill gets higher than the amount of cash available

   //At each iteration inreases the tip and the bill to the next multiple of 5

   while(bill<=cash){

      //Calculates the percentage of tips in the total bill

      percentage = ((double)tip/(double)bill)*100;

      if(percentage>=5 && percentage<=10){

         ways++;

      }  

      if(percentage>10){

         return ways;

      }

      tip+=5;

      bill+=5;

   }

   return ways;

}

void main(){

   //The long int is given in order tor deal with very large numbers. You may use int of necessary.  

   long int bill;

   long int cash;

   long int numberofways = 0;

   //Takes the bill and cash as input

   printf("Enter the bill and the cash: ");

   scanf("%ld", &bill);

   scanf("%ld", &cash);

   //Calls the function to calculate the number of ways

   numberofways = possible_payments(bill,cash);

   //Display the number of ways

   printf("The number of ways are: %ld\n", numberofways);

}

CODE SCREENSHOT

OUTPUT: