(UVA) Dollars - Solution

Link to the problem: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=653&page=show_problem&problem=83

The solution below used the concept of Coin Change, related to Dynamic Programming, to solve this problem.

Tip: Instead of manipulating float variables, it is better to convert the entry to an integer.


import java.io.*;
import java.util.*;

class Main {
    public int[] coins = {10000, 5000, 2000, 1000, 500, 200, 100, 50, 20, 10, 5};
    public long[][] matrix;
   
    public long coinChange(int money, int indexCoins) {
        if (money == 0) {
            return 1;
        }
        else if (money < 0 || indexCoins < 0) {
            return 0;
        }
       
        if (matrix[money][indexCoins] != -1) {
            return matrix[money][indexCoins];
        }
       
        long use = coinChange(money-coins[indexCoins], indexCoins);
        long notUse = coinChange(money, indexCoins-1);
        matrix[money][indexCoins] = use+notUse;
        return matrix[money][indexCoins];
    }
   
    public void process() throws NumberFormatException, IOException {
        Scanner sc = new Scanner(System.in);
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
       
        matrix = new long[30001][11];
        for (int i = 0; i < 30001; i++) {
            for (int j = 0; j < 11; j++) {
                matrix[i][j] = -1;
            }
        }
       
        double entry = sc.nextDouble();
        while (entry != 0.00) {
            int money = (int)(entry*100+0.000000001); // better to use an int than a double

            System.out.printf("%6.2f%17d\n", entry, coinChange(money, 10));
           
            entry = sc.nextDouble();
        }
               
        bw.flush();
        bw.close();
       
        return;
    }
   
    public static void main(String[] args) throws NumberFormatException, IOException {
        Main m = new Main();
        m.process();
       
        System.exit(0);
    }
}