Stanford CS106A Assignment 2 Find Range Solution

The Find Range solution requires some serious logic. Here is the problem:

Here is my solution, also available on gist:

The hardest part for me was actually figuring out how to use the while loop outside of Karel’s world, where all the while loops started with “while (frontIsClear)” and where they ended with there being a wall in front of Karel. Here, the while loop needs to run as long as the number the user provides is not equivalent to the sentinal, so you have to stop the loop by assigning the sentinal to the first number.

 * File:
 * Name: 
 * Section Leader: 
 * --------------------
 * This file is the starter file for the FindRange problem.

import acm.program.*;

public class FindRange extends ConsoleProgram {

	private static final int sentinal = 0;

	public void run() {
	private void displayWelcomeMessage() {
		println("This program finds the largest and smallest numbers");
	private void findRange() {
		int firstNumber = readInt("?"); //asking user for the first number
		if (firstNumber == sentinal) { 
			println("this is not a valid first value");
		} //if the first number is the sentinal, displays message
		int smallestNumber = firstNumber; //the first number is currently the smallest number
		int largestNumber = firstNumber; //the first number is also the largest number

		/*Pre-condition: the first number does not equal to the sentinal.
		 * compares each new number the user enters to the existing smallest and largest numbers, 
		 * and stores them as the smallest or largest if they are smallest or largest

		while ( firstNumber != sentinal) { 
			int secondNumber = readInt ("?"); //requests user to input the next number
			if (secondNumber < smallestNumber) { //compares the new number to the smallest number
				if (secondNumber != sentinal) {
					smallestNumber = secondNumber;
			// if the new number is the smaller than the smallest number, 
				//it is now stored as the smallest number
			if (secondNumber > largestNumber) { //compares the new number to the largest number
				if (secondNumber != sentinal) {
					largestNumber = secondNumber;
			//if the new number is larger than the largets number, 
				//it is now stored as the largest number
			if(secondNumber == sentinal) { //if the new number is equal to the sentinal
				println ("smallest: " + smallestNumber); //prints out smallest number
				println ("largest: " + largestNumber); //pringt out largest number
				firstNumber = sentinal; //assigns "sentinal" to the first number to stop the while loop


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