Nick Price CashRegister Solution

CashRegister.java

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+import java.io.File;
+import java.util.Random;
+import java.io.FileNotFoundException;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.Scanner;
+
+public class CashRegister {
+	public static void main (String[] args) throws IOException, FileNotFoundException {
+		//Try block used if file fails to open
+		try {
+			//Open File
+			File testData = new File(System.getProperty("user.dir") + "\\testdata.txt");
+			//Write to File
+			FileWriter fWriter = new FileWriter(testData, true);
+			//Read data from File
+			Scanner fReader = new Scanner(testData);
+			fWriter.write("\n");
+			while (fReader.hasNextLine()) {
+				String input = fReader.nextLine();
+				//Error checking format
+				if (input.matches("\\d*.\\d{2},\\d*.\\d{2}") || input.matches("\\d*.\\d{2},\\d*") || input.matches("\\d*,\\d*.\\d{2}") || input.matches("\\d*,\\d*")) {
+					String[] data = input.split(",");
+					int costInCents = (int) (Double.parseDouble(data[0]) * 100);
+					int paidInCents = (int) (Double.parseDouble(data[1]) * 100);
+					if (costInCents > paidInCents) {
+						fWriter.write("Cost too high.\n");
+					}
+					else {
+						//If amount in cents is divisible by 3, use randomized solution
+						fWriter.write(solution(paidInCents - costInCents, costInCents % 3 == 0) + "\n");
+					}
+				}
+				else {
+					fWriter.write("Invalid Formatting.\n");
+				}
+			}
+			fWriter.close();
+			fReader.close();
+		} catch (FileNotFoundException e) {
+			System.out.println("File not found.");
+		} catch (IOException e) {
+			System.out.println("IOException.");
+		}
+
+	}
+
+	public static String solution(int difference, boolean isDivisible) {
+		Random rand = new Random();
+		//Solution built in this string
+		String solution = "";
+		// Variable to track how many of each change increment to give
+		int multiple = 0;
+		if (difference >= 10000) {
+			multiple = difference / 10000;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 10000;
+				solution = solution + Integer.toString(multiple) + " hundred" + addLetterS(multiple);
+			}
+		}
+		if (difference >= 5000) {
+			multiple = difference / 5000;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 5000;
+				if (multiple == 1) {
+					solution = solution + Integer.toString(multiple) + " fifty,";
+				}
+				else {
+					solution = solution + Integer.toString(multiple) + " fifties,";
+				}
+			}
+		}
+		if (difference >= 2000) {
+			multiple = difference / 2000;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 2000;
+				if (multiple == 1) {
+					solution = solution + Integer.toString(multiple) + " twenty,";
+				}
+				else {
+					solution = solution + Integer.toString(multiple) + " twenties,";
+				}
+			}
+		}
+		if (difference >= 1000) {
+			multiple = difference / 1000;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 1000;
+				solution = solution + Integer.toString(multiple) + " ten" + addLetterS(multiple);
+			}
+		}
+		if (difference >= 500) {
+			multiple = difference / 500;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 500;
+				solution = solution + Integer.toString(multiple) + " five" + addLetterS(multiple); 
+			}
+		}
+		if (difference >= 100) {
+			multiple = difference / 100;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 100;
+				solution = solution + Integer.toString(multiple) + " dollar" + addLetterS(multiple);
+			}
+		}
+		if (difference >= 25) {
+			multiple = difference / 25;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 25;
+				solution = solution + Integer.toString(multiple) + " quarter" + addLetterS(multiple);
+			}
+		}
+		if (difference >= 10) {
+			multiple = difference / 10;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 10;
+				solution = solution + Integer.toString(multiple) + " dime" + addLetterS(multiple);
+			}
+		}
+		if (difference >= 5) {
+			multiple = difference / 5;
+			if (isDivisible)
+				multiple = rand.nextInt(multiple);
+			if (multiple != 0) {
+				difference -= multiple * 5;
+				solution = solution + Integer.toString(multiple) + " nickel" + addLetterS(multiple);
+			}
+		}
+		if (difference > 0) {
+			solution = solution + Integer.toString(difference);
+			if (difference == 1) {
+				solution += " penny";
+			}
+			else {
+				solution += " pennies";
+			}
+		}
+		//Error checking for exact change
+		if (solution.length() != 0) {
+			//Removes trailing comma if present
+			if (solution.charAt(solution.length() - 1) == ',') {
+				solution = solution.substring(0, solution.length() - 1);
+			}
+			return solution;
+		}
+		else {
+			return "No Change Given.";	
+		}
+	}
+
+
+	// Helper function to format solution string
+	public static String addLetterS(int multiple) {
+		if (multiple > 1)
+			return "s,";
+		return ",";
+	}
+}

testdata.txt

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+2.12,3.00
+1.97,2.00
+3.33,5.00