I am trying to create java application.
It ask questions and have 4 choices for each question.
I want to count total right and wrong answers selected by the user.
I am using function like this-
public void checkAnswer(String choice)
{
int correctcount=0;
int wrongcount=0;
if(counter==1) {
if (choice.equalsIgnoreCase("a")) {
correctAnswerDisplay();
correctcount = correct count + 1;
} else {
wrongAnswerDisplay();
wrongcount = wroungcount + 1;
}
}
else if(counter==2) {
if (choice.equalsIgnoreCase("d")) {
correctAnswerDisplay();
} else {
wrongAnswerDisplay();
}
}
Basically I hardcoded answers for each question.
For e.g- For this question, correct answer is "A". so I said if its "a" call the correct answer function else wrong answer in question#1. Counter variable is to display next questions
How can i calculate total right and wrong answer of all question. I have allowed users to select another option if they answer wrong, so they don't get to next question until they select right answer. But every time when they select wrong answer counter will add more numbers it should allow only 1 addition and stop there.
Also, lets says i selected wrong answer, I won't get next question until i hit continue button, and continue button appears only when i select correct answer. So if i select wrong answer 2 times, counter will be 2. It should work as i select wrong answer even three times, total wrong answer count should be just 1. and person will always select correct answer once for each question because continue button doesn't appear until then. So it should not increase correct counter if wrong answer was selected first.
Sorry I am a new programmer. Please help.
package org.test.main;
import java.util.Scanner;
public class TestMain {
public int correctcount = 0;
public int wrongcount = 0;
public int counter = 1; // lets assume you have counter as 1 to start with
public void checkAnswer(String choice) {
if (counter == 1) {
if (choice.equalsIgnoreCase("a")) {
correctAnswerDisplay();
correctcount = correctcount + 1;
} else {
wrongAnswerDisplay();
wrongcount = wrongcount + 1;
}
} else if (counter == 2) {
if (choice.equalsIgnoreCase("d")) {
correctAnswerDisplay();
correctcount = correctcount + 1;
} else {
wrongAnswerDisplay();
wrongcount = wrongcount + 1;
}
}
}
private void wrongAnswerDisplay() {
System.out.println("Wrong");
}
private void correctAnswerDisplay() {
System.out.println("Correct");
}
public static void main(String[] args) {
TestMain testM = new TestMain();
Scanner scanNext = new Scanner(System.in);
for(int i = 0; i < 2;i++) {
System.out.print("Question#"+(i+1)+": ");
String ans = scanNext.nextLine();
testM.checkAnswer(ans);
testM.counter++;
}
System.out.println("Number of Correct Answer:" + testM.correctcount);
System.out.println("Number of Wrong Answer:" + testM.wrongcount);
}
}
Make your correctcount and wrongcount as instance variable. because every time you call the method checkAnswer(), 0 will be assigned in the 2 variables you created in your method.
I tried to simulate your logic. so try this. The numbers of question and the answers are hardcoded. so change it in your logic to be dynamic. I write this code to understand how the incrementation works.
It is a really good thing that you have started using communities like Stackoverflow.
Form the question it is clear that there is a continue button which will be enabled only if you select the correct answer. (Then there is no point in counting correct answers since with such a button, at the end you will have all the questions answered correctly. Anyway if you really want this logic to work try the following.)
Let's create a method incrementWrongCount() to increment the variable wrongcount.
public class AnswerTester{
int correctcount = 0;
int wrongcount = 0;
/*Following variable indicates whether you have selected any wrong answers before
selecting the right answer. Obviously its default value is false since you
have selected no wrong answers (in fact no answers) when you first
you first answers a question*/
boolean wronganswerselected = false;
public void checkAnswer(int counter, String choice){
if(counter==1) {
if (choice.equalsIgnoreCase("a")) {
correctAnswerDisplay();
correctcount = correctcount + 1;
incrementWrongCount();
wronganswerselected = false;//For the next question
enableContinueButton();
} else {
wrongAnswerDisplay();
wronganswerselected = true;//just indicate that you have selected a wrong answer. We will increment wrong count in incrementWrongCount()
disableContinueButton();
}
} else if(counter==2) {
if (choice.equalsIgnoreCase("d")) {
correctAnswerDisplay();
correctcount = correctcount + 1;
incrementWrongCount();
wronganswerselected = false;
enableContinueButton();
} else {
wrongAnswerDisplay();
wronganswerselected = true;
disableContinueButton();
}
}
}
private void incrementWrongCount(){
if(wronganswerselected){//Should increment wrongcount only if the user have selected atleast one wrong answer.
wrongcount = wrongcount + 1;
}
}
private void correctAnswerDisplay(){
System.out.println("Correct..");
}
private void wrongAnswerDisplay(){
System.out.println("Wrong..");
}
public int getCorrectCount(){
return correctcount;
}
public int getWrongCount(){
return wrongcount;
}
}
Its a good practice to use switch instead of if...else if to match a variable against multiple values.
Related
I'm a high schooler in apcs and I'm trying to practice these for the test. The code should return whether a new object was created. Also, the moveUp method doesn't allow me to call it using the scoreboard list (e.g. "scoreboard.move(int x)". Please explain why I'm wrong, but don't solve it.
public boolean newScore(String name, int score)
{
/* Implement your answer to part (b) here */
for (int ind = 0; ind < scoreboard.size(); ind++) {
Player player = scoreboard.get(ind);
if (player.getName().equalsIgnoreCase(name)) {
player.updateScore(score);
moveUp(scoreboard.indexOf(player));
return true;
} else {
Player p = new Player(name, score);
scoreboard.add(p);
p.updateScore(score);
moveUp(scoreboard.indexOf(p));
return false;
}
}
}
Question:
In this problem, the scenario we are evaluating is the following: You're standing at the base of a staircase and are heading to the top. A small stride will move up one stair, and a large stride advances two. You want to count the number of ways to climb the entire staircase based on different combinations of large and small strides. For example, a staircase of three steps can be climbed in three different ways: three small strides, one small stride followed by one large stride, or one large followed by one small.
The call of waysToClimb(3) should produce the following output:
1 1 1,
1 2,
2 1
My code:
public static void waysToClimb(int n){
if(n == 0)
System.out.print("");
else if(n == 1)
System.out.print("1");
else {
System.out.print("1 ");
waysToClimb(n - 1);
System.out.print(",");
System.out.print("2 ");
waysToClimb(n - 2);
}
}
My output:
1 1 1,
2,
2 1
My recursion doesn't seem to remember the path it took any idea how to fix it?
Edit:
Thank you guys for the responses. Sorry for the late reply
I figured it out
public static void waysToClimb(int n){
String s ="[";
int p=0;
com(s,p,n);
}
public static void com(String s,int p,int n){
if(n==0 && p==2)
System.out.print(s.substring(0,s.length()-2)+"]");
else if(n==0 && p !=0)
System.out.print(s+"");
else if(n==0 && p==0)
System.out.print("");
else if(n==1)
System.out.print(s+"1]");
else {
com(s+"1, ",1,n-1);
System.out.println();
com(s+"2, ",2,n-2);
}
}
If you explicity want to print all paths (different than counting them or finding a specific one), you need to store them all the way down to 0.
public static void waysToClimb(int n, List<Integer> path)
{
if (n == 0)
{
// print whole path
for (Integer i: path)
{
System.out.print(i + " ");
}
System.out.println();
}
else if (n == 1)
{
List<Integer> newPath = new ArrayList<Integer>(path);
newPath.add(1);
waysToClimb(n-1, newPath);
}
else if (n > 1)
{
List<Integer> newPath1 = new ArrayList<Integer>(path);
newPath1.add(1);
waysToClimb(n-1, newPath1);
List<Integer> newPath2 = new ArrayList<Integer>(path);
newPath2.add(2);
waysToClimb(n-2, newPath2);
}
}
initial call: waysToClimb(5, new ArrayList<Integer>());
Below mentioned solution will work similar to Depth First Search, it will explore one path. Once a path is completed, it will backtrace and explore other paths:
public class Demo {
private static LinkedList<Integer> ll = new LinkedList<Integer>(){{ add(1);add(2);}};
public static void main(String args[]) {
waysToClimb(4, "");
}
public static void waysToClimb(int n, String res) {
if (ll.peek() > n)
System.out.println(res);
else {
for (Integer elem : ll) {
if(n-elem >= 0)
waysToClimb(n - elem, res + String.valueOf(elem) + " ");
}
}
}
}
public class Test2 {
public int climbStairs(int n) {
// List of lists to store all the combinations
List<List<Integer>> ans = new ArrayList<List<Integer>>();
// initially, sending in an empty list that will store the first combination
csHelper(n, new ArrayList<Integer>(), ans);
// a helper method to print list of lists
print2dList(ans);
return ans.size();
}
private void csHelper(int n, List<Integer> l, List<List<Integer>> ans) {
// if there are no more stairs to climb, add the current combination to ans list
if(n == 0) {
ans.add(new ArrayList<Integer>(l));
}
// a necessary check that prevent user at (n-1)th stair to climb using 2 stairs
if(n < 0) {
return;
}
int currStep = 0;
// i varies from 1 to 2 as we have 2 choices i.e. to either climb using 1 or 2 steps
for(int i = 1; i <= 2; i++) {
// climbing using step 1 when i = 1 and using 2 when i = 2
currStep += 1;
// adding current step to the arraylist(check parameter of this method)
l.add(currStep);
// make a recursive call with less number of stairs left to climb
csHelper(n - currStep, l, ans);
l.remove(l.size() - 1);
}
}
private void print2dList(List<List<Integer>> ans) {
for (int i = 0; i < ans.size(); i++) {
for (int j = 0; j < ans.get(i).size(); j++) {
System.out.print(ans.get(i).get(j) + " ");
}
System.out.println();
}
}
public static void main(String[] args) {
Test2 t = new Test2();
t.climbStairs(3);
}
}
Please note this solution will timeout for larger inputs as this isn't a memoized recursive solution and can throw MLE(as I create a new list when a combination is found).
Hope this helps.
if anyone looking for a python solution, for this problem.
def way_to_climb(n, path=None, val=None):
path = [] if path is None else path
val = [] if val is None else val
if n==0:
val.append(path)
elif n==1:
new_path = path.copy()
new_path.append(1)
way_to_climb(n-1, new_path, val)
elif n>1:
new_path1 = path.copy()
new_path1.append(1)
way_to_climb(n-1, new_path1, val)
new_path2 = path.copy()
new_path2.append(2)
way_to_climb(n-2, new_path2, val)
return val
Note: it is based on the #unlut solution, here OP has used a top-down recursive approach. This solution is for all people who looking for all combination of staircase problem in python, no python question for this so i have added a python solution here
if we use a bottom-up approach and use memorization, then we can solve the problem faster.
Even though you did find the correct answer to the problem with your code, you can still improve upon it by using just one if to check if the steps left is 0. I used a switch to check the amount of steps taken because there are only 3 options, 0, 1, or 2. I also renamed the variables that were used to make the code more understandable to anyone seeing it for the first time, as it is quite confusing if you are just using one letter variable names. Even with all these changes the codes run the same, I just thought it might be better to add some of these things for others who might view this question in the future.
public static void climbStairsHelper(String pathStr, int stepsTaken, int stepsLeft)
{
if(stepsLeft == 0)
{
switch(stepsTaken)
{
case 2:
System.out.print(pathStr.substring(0, pathStr.length() - 2) + "]");
break;
case 1:
System.out.print(pathStr + "");
break;
case 0:
System.out.print("");
break;
}
}
else if(stepsLeft == 1)
{
System.out.print(pathStr + "1]");
}
else
{
climbStairsHelper(pathStr + "1, ", 1, stepsLeft - 1);
System.out.println();
climbStairsHelper(pathStr + "2, ", 2, stepsLeft - 2);
}
}`
`
So I did search and read abut every factorial listing on this site but I cannot seem to figure out what is wrong with my code. Iv tried multiple different return methods but they all keep failing. Any ideas?
public class RecursivelyPrintFactorial {
public static void printFactorial(int factCounter, int factValue) {
int nextCounter = 0;
int nextValue = 0;
if (factCounter == 0) // Base case: 0! = 1
System.out.println("1");
}
else if (factCounter == 1) // Base case: print 1 and result
System.out.println(factCounter + " = " + factValue);
}
else { // Recursive case
System.out.print(factCounter + " * ");
nextCounter = factCounter - 1;
nextValue = nextCounter * factValue;
}
return factValue * printFactorial(factValue - factCounter);
}
}
public static void main (String [] args) {
int userVal = 0;
userVal = 5;
System.out.print(userVal + "! = ");
printFactorial(userVal, userVal);
}
}
I have a feeling I have the equation incorrect in my return but iv tried every combination I can think of. Its driving me insane. Every one reports an error. Any ideas?
return factValue * printFactorial(factValue - factCounter);
I assume that you should be using the "next" values instead of these.
Edit: Also note that the function takes two parameters and is void. Returning factValue times void doesn't make sense.
Just one last part remaining in the ChatBot. I need to figure out a way to modify the chatbot class so
that it occasionally (say, 30% of the time) returns a randomly-‐generated standard reply to user input one of at least five possible replies, like “LOL”, “OMG”, “You don’t say”, “Really?”, or “I see”.
Edit: Applied recommended changes:
import java.util.Random;
import java.util.Scanner;
public class ChatBot
{
private int responseCount = 0;
public String getResponse(String value)
{
String X = longestWord(value);
this.responseCount++;
if (responseCount == 10)
{
return "Sorry, but our time is up. I can't talk with you any longer.";
}
if (value.contains("you"))
{
return "I'm not important. Let's talk about you instead.";
}
else if (X.length() <= 3)
{
return "Maybe we should move on. Is there anything else you would like to talk about?";
}
else if (X.length() == 4)
{
return "Tell me more about " + X;
}
else if (X.length() == 5)
{
return "Why do you think " + X + " is important?";
}
else if (X.length() <=9)
{
return "Now we are getting somewhere. How does " + X + " affect you the most?";
}
return getRandomResponse();
}
public String longestWord(String value){
Scanner input = new Scanner (value);
String longest = new String();
longest = "";
while (input.hasNext())
{
String temp = input.next();
if(temp.length() > longest.length())
{
longest = temp;
}
}
return longest;
}
private String getRandomResponse()
{
String [] responses = {"OMG", "LOL", "You don't say", "Really?", "I See"};
return responses [(int)(Math.random() * responses.length)];
}
}
The problem is, it keeps returning the same response, instead of one of the five responses given. Any help would me much appreciated, thank you!
Edit:It's now giving only the random responses, and overriding every other response in the getResponse() method.
Given your logic, your getRandomResponse method should always return "OMG". This is because on the first run of the loop in that method, counter = 1. Thus the first if statement will run and will return "OMG" exitting the method. A nicer equivalent might putting all teh responses into an array and returning a random value from it, rather than doing somehting strange with iteration:
String[] responses = {"OMG", "LOL", "You don't say", "Really?", "I See"};
return responses[(int)(Math.random() * responses.length)];
In getRandomResponse, you make a random number generator using Random(), but you never use it. Then in your for loop, you execute your decision-making tree but use a variable counter that always begins at 0. Then on the first time through your loop, the first if statement will execute because 0 < 5, so "OMG" is returned.
Edit: I just noticed something else that is not going to work in your code:
Random randomNumber = new Random();
for (int counter =0; counter<10; counter++)
{
counter = randomNumber.nextInt();
You're trying to use counter to do two different things: you are trying to run this loop 10 times, but you're also using it to store random values.
Time for my daily newbie Java question :-D
I must not be understanding conditionals in a while loop correctly.
I have this:
while (true){
if (){
...
} else {
...
}
if (){
...
} else {
...
}
if (SENTINEL){
break;
}
}
The first if/else statement is working, and the sentinel is working, but the second if statement gets skipped. If I flip the first and second if statement, then the first if statement still always gets executed and skips the second. What am I missing?
Can I have two if/else statements in one block like this?
I'll include the whole code, though it's pretty ugly, and I'm sure I'll get lots of people telling me better ways of doing this. I don't mind learning better ways, but for now, I just want an answer to this looping question. thanks!
public class FindRange extends ConsoleProgram {
private static final int SENTINEL = 0;
int value = 0;
int highNumber = 0;
int latestValue = 0;
int lowNumber = 0;
public void run() {
addNumbers();
}
private void addNumbers(){
value = readInt("Enter number:");
while(true){
if (value == SENTINEL){
break;
}
latestValue = readInt("Enter number:");
getHighNumber();
getLowNumber();
if (latestValue == SENTINEL){
break;
}
}
println("High Number is "+highNumber+".");
println("Low Number is "+lowNumber+".");
}
private void getHighNumber(){
if (latestValue >= value){
highNumber = latestValue;
}else {
highNumber = value;
}
}
private void getLowNumber(){
if (latestValue <= value){
lowNumber = latestValue;
}else {
lowNumber = value;
}
}
}
Are you trying to find the minimum and maximum of a series of numbers? If so, you should definitely use Math.min() and Math.max(). It's much clearer that way and you can do away with the if statements. It's also simple enough to do it in the loop with local variables instead of fields.
The common idiom is something like this:
minValue = Math.min(minValue, candidateValue);
maxValue = Math.max(maxValue, candidatevalue);
It's possible that the behavior you're seeing comes from the fact that you are always comparing the latest value to the initial value. The initial value will never change-- so if you put in the following input:
20, 60, 50
the high value that gets reported would be 50. That's because 50 is the most recent value to be greater than 20. I think you probably mean to compare the latest value to the high value, no?
You can definitely have 2 if/else blocks within the loop; however if your sentinel gets hit the loop will exit.
Posting the entire block would help.
What will happen (after reading the posted code) is when any new value you enter within the loop is greater than the original value, lowNumber is set back to the original. So for example if your input is:
7 6 5 8
Your corresponding low number values will be:
7 6 5 7
Which is incorrect. What you could do is toast the "value" variable altogether, set your low and high to the original value, then compare latest with low and high in the get* methods.
Shouldn't you be setting value = latestValue at the bottom of your while loop?
Value never gets updated after the initial read... maybe something like this:
public class FindRange extends ConsoleProgram {
private static final int SENTINEL = 0;
public void run() {
addNumbers();
}
private void addNumbers() {
int value = 0;
// Set this to highest possible value
int highNumber = Integer.MIN_VALUE;
// Set this to lowest possible value
int lowNumber = Integer.MAX_VALUE;
while (true) {
value = readInt("Enter number:");
if (value == SENTINEL)
break;
lowNumber = Math.min(lowNumber, value);
highNumber = Math.max(highNumber, value);
}
println("High Number is " + Integer.toString(highNumber) + ".");
println("Low Number is " + Integer.toString(lowNumber) + ".");
}
}