Bytelandian Coins - wrong answer

general
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1

Not sure what is wrong with this code. These are the input/output that I get
12 --> 13
13 --> 16
When I submit it, the system tell wrong answer. Any suggestions will be appreciated.

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashMap;


public class ByteLandianColdCoin {
public static HashMap map = new HashMap(); 
public static void main(String[] args) {
	try {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String s;
		while ((s= br.readLine()) != null && s.length()!=0)
		{
			double i = Double.parseDouble(s.trim());
			System.out.println(new Double(change(i, "")).longValue());
		}
	} catch (Exception e) {
		System.err.println("Error:" + e.getMessage());
	}

}

public static double change(double coin, String ind)
{
	//System.out.println(ind+" coin: "+coin);
	Double ddollar = ((Double)map.get(coin));
	if(ddollar!= null)
	{
		//System.out.println(ind+" dollar:"+ddollar.doubleValue());
		return ddollar.intValue();
	}

	ind = ind+" * ";
	//System.out.println(ind+" in change -"+coin);

	if(coin <12)
	{
		map.put(coin, coin);
		//System.out.println(ind+map);
		return coin;
	}

	double dollar = change(Math.ceil(coin/2), ind)+change(Math.ceil(coin/3), ind)+change(Math.ceil(coin/4), ind);
	dollar = coin>dollar?coin:dollar;


	map.put(coin, dollar);
	//System.out.println(ind+map);
	//System.out.println(ind+" dollar:"+dollar);
	return dollar;
}
}
2

Analysis,

  1. You have parsed input as a Double and printed out its longValue but in your change function you have returned intValue of coins if present in the map.
  2. The recurrence you used dollar = change(Math.ceil(coin/2), ind)+change(Math.ceil(coin/3), ind)+change(Math.ceil(coin/4), ind) seems incorrect.
  3. I am not sure whether you are allowed to write to the error stream on Codechef.

Suggestions,

  1. Use Long instead of Double.
  2. Remove ind if its not used.
  3. Re-read the question to get the correct recurrence.
  4. Check FAQ to make sure if you are allowed to write to error stream.
3

use floor instead of ceil bcoz in question its written “rounded down” and not “rounded up”