Question

Suppose we want to make change for N cents, using the least number of coins of denominations {1, 5, 10} cents (Different from the US currency system!). Consider the following greedy strategy: suppose the amount left to change is M, take the largest coin that is no more than M; subtract this coin's value from M, and repeat.

1. Implement the Greedy Coin Changing Algorithm in Java.

public class Coinchange {
   public static int greedycoinchange(int givenvalue, int[] givencoins)
   {
       // Complete the code here to make change of givenvalue using coins in the array givencoins
       // Minimize the number of coins used
       // Input: Coin denominations in array givencoins are already sorted in descending order
       // Output: The number of coins used to make change of givenvalue          
   }
  
   public static void main(String[] args) {
       int n = 0; // n cents
       Scanner reader = new Scanner(System.in);
       System.out.println("Please enter the value you want to make change: ");
       n = reader.nextInt();
       int[] coins = {25, 10, 5, 1};
      
       System.out.println("used "+ greedycoinchange(n, coins)+" coins for "+ n + " cents");  
   }
}

Answer 1

code:

import java.util.*;
public class Coinchange {
public static int greedycoinchange(int givenvalue, int[] givencoins)
{
Vector<Integer> t_coins = new Vector<>(); /*here we create a vector of store a coins value*/
int n=givencoins.length; /*here we find a size of givencoins array and store into n*/
  
for (int i = 0; i < n; i++) /*take one for loop for all the coins value*/   
{
/* Find coins */
while (givenvalue >= givencoins[i]) /*here we check if value grater that coins value than we take that coins*/
{
givenvalue -= givencoins[i]; /*substract that coins value from given value*/
t_coins.add(givencoins[i]); /*add coin into vector*/
}
}
return t_coins.size(); /*return the size of vector*/
}
  
public static void main(String[] args) {
int n = 0; // n cents
Scanner reader = new Scanner(System.in);   
System.out.println("Please enter the value you want to make change: ");
n = reader.nextInt(); /*take value from user*/
int[] coins = {25, 10, 5, 1};
  
System.out.println("used "+ greedycoinchange(n, coins)+" coins for "+ n + " cents"); /*print total used coins*/
}
}