package username.dynamic;

import java.util.Vector;

/**
 * A simple program to compute the fewest coins for a particular
 * price.
 *
 * @author Samuel A. Rebelsky
 * @author CSC152 2006S
 * @version 1.0 of April 2006
 */
public class NewerCoins
{
  /**
   * Given a set of denominations, compute the fewest coins
   * for a particular price.
   */
  public static Vector<Integer> fewestCoins(int[] denominations, int price)
    throws Exception
  {
    // Sanity check
    if (price < 0) {
      throw new Exception("Invalid price");
    }
    // Easy case: No cost implies no coins
    else if (price == 0) {
      return new Vector<Integer>();
    }
    // Normal case: Check each coin and see which one works best.
    else {
      Vector<Integer> best = null;
      for (int i = 0; i < denominations.length; i++) {
        int newprice = price - denominations[i];
        if (newprice >= 0) {
          try {
            Vector<Integer> guess = fewestCoins(denominations, newprice);
            if ((best == null) || (guess.size() < best.size())) {
              best = (Vector<Integer>) guess.clone();
              best.add(new Integer(denominations[i]));
            }
          } // try
          catch (Exception e) {
            // Of well, that coin didn't work.
          } // catch(Exception
        } // if (newprice >= 0)
      }  // for
      if (best != null) {
        return best;
      }
      else {
        throw new Exception("Cannnot make exact change for " + price);
      }
    } // normal case
  } // fewestCoins(int[], int)
} // class NewerCoins