package username.dynamic;

/**
 * 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 BetterCoins
{
  /**
   * Given a set of denominations, compute the fewest coins
   * for a particular price.
   */
  public static int[] fewestCoins(int[] denominations, int price)
    throws Exception
  {
    int[] cache = new int[price+1];
    int[][] newcache = new int[price+1][denominations.length];

    fewestCoins(denominations, price, cache, newcache);

    // Tony: Return the "alternate cache"
    return newcache[price];
  }

  public static int fewestCoins(int[] denominations, int price, int[] cache, int[][] newcache) 
    throws Exception
  {
    // Sanity check
    if (price < 0) {
      throw new Exception("Invalid price");
    }
    // Easy case: No cost implies no coins
    else if (price == 0) {
      return 0;
    }
    else if (cache[price] == -1) {
      // Betsy: We need to check cache[0][price] instead

      throw new Exception("Cannot make change for " + price);
    }
    else if (cache[price] != 0) {
      // Betsy: Check if any of the slots has 0
      // Tony: Return results[price]
      return cache[price];
    }
    // Normal case: Check each coin and see which one works best.
    else {
      int best = Integer.MAX_VALUE;
      for (int i = 0; i < denominations.length; i++) {
        int newprice = price - denominations[i];
        if (newprice >= 0) {
          try {
            // Betsy: Sum the values in the array
            // Tony: Use the original cache
            int guess = fewestCoins(denominations, newprice, cache, newcache);
            if (guess < best) {
              best = guess+1;
        // Betsy: Grab the subarray from the best one and increment the number of the given coin
              for (int j = 0; j < denominations.length; j++) {
                newcache[price][j] = newcache[newprice][j];
              } // for
              newcache[price][i] = newcache[price][i]+1;
        // Tony: Set the values in the parallel array
              cache[price] = best;
            }
          } // try
          catch (Exception e) {
            // Of well, that coin didn't work.
          } // catch(Exception
        } // if (newprice >= 0)
      }  // for
      if (best != Integer.MAX_VALUE) {
        return cache[price];
      }
      else {
        cache[price] = -1; 
        throw new Exception("Cannot make exact change for " + price);
      }
    } // normal case
  } // fewestCoins(int[], int)
} // class BetterCoins