Compare randomly generated number between user input - java

I am a cs student and i have an assignment that I'm not sure how to complete here is the prompt,
"Develop a Java console application for a simple game of guessing at a secret five-digit code (a random number from 10000 to 99999). When the user enters a guess at the code, the program outputs two values: the number of digits in the guess that are in the correct position and the sum of those digits. For example, if the secret code is 53840 and the user guesses 83241, the digits 3 and 4 are in the correct positions. Thus, the program should respond with 2 (number of correct digits) and 7 (sum of the correct digits). Allow the user to guess until s/he gets it correct."
basically the part I am stuck on is how to find which numbers are correct numbers in common and add them together. Here is my code so far.
Random rand = new Random();
int secretNumber = rand.nextInt(99999 - 10000 + 1) + 10000;
System.out.println(secretNumber);
Scanner consoleScanner = new Scanner(System.in);
int guess;
do {
System.out.print("Please enter a 5-digit code (your guess): ");
guess = consoleScanner.nextInt();
if (guess == secretNumber)
System.out.println("****HOORAY! You solved it. You are so smart****");
else if (guess > 99999 || guess < 10000)
System.out.println("Guess must be a 5-digit code between 10000 and 99999.\n");
} while (guess != secretNumber);
any help would be greatly appreciated.

You have a number. I'm going to call it blarg. Let's say blarg is a double.
You also have a number called input.
String blargString = Double.toString(blarg);
String inputString = Double.toString(input);
ArrayList<Integer[]> indexNumberList = new ArrayList<Integer[]>();
int n = 0;
for (char c : blargString.toCharArray()) {
n++;
if (c == inputString.toCharArray()[n]) {
Integer[] entry = new Integer[2];
entry[0] = n;
entry[1] = Character.getNumericValue(c);
indexNumberList.add(entry);
}
}
Now you have a list of Integer pairs. Do what you will with it. For each pair, entry[0] is the location in the number, the index, and entry[1] is the value.

Integer.toString(int) returns the string representation of an integer. You can compare the strings returned from Integer.toString(secretNumber) and Integer.toString(guess) character-by-character to determine which digits differ.

Here's how I'd go about solving that problem. My solution is quick but probably naive. Convert the number the user enters and your generated number to strings and then to two arrays of 5 bytes each. Scan through the arrays and compare two corresponding bytes at a time. Let the user know that the position of a digit was guessed correctly if two corresponding bytes are equal. Below, I show you how you can get the array of bytes you need.
byte[] a = Integer.toString(guess).getBytes();
byte[] b = Integer.toString(secretNumber).getBytes();

So you have 2 5-digit numbers that you need to compare.
I would recommend you to do this with a loop:
//Make copies so we can modify the value without changing
// the original ones.
int tempGuess = guess;
int tempSecret = secretNumber;
//Create variables for the output
int numCorrect = 0;
int sumCorrect = 0;
for(int i = 0; i < 5; i++) //for each of the digits
{
//Get the last digit of each number and remove it from the number:
int lastGuess = tempGuess%10;
tempGuess/=10;
int lastSecret = tempSecret%10;
tempSecret/=10;
//Compare both digits:
if(lastGuess == lastSecret)
{
//Found a match: Increas number of found by one
numCorrect++;
//Add value of digit to sum
sumCorrect += lastGuess;
}
}
//numCorrect now contains the number of matching digits
//sumCorrect now contains the sum of matchig digits

The solution can be address like:
define an counter for the coincidences and an accumulator for the adition of those
make a loop through the guess and compare char by char if the input at any given char match the random number, if so:
increase counter by one and add to the accumulator the integer value of the char.
Example:
final String s1 = Integer.toString(secretNumber);
final String s2 = Integer.toString(guess);
for (int i = 0; i < s1.length(); i++) {
if (s1.charAt(i) == s2.charAt(i)) {
counter++;
acumm = Character.getNumericValue(s1.charAt(i));
}
}
System.out.println("There is/are " + counter + " coincidences");
System.out.println("The addition of those is: " + acumm);

you could use integers, use modulus and divide to get the digit you want.
53840 % 100000 / 10000 = 5
53840 % 10000 / 1000 = 3
loop and compare

Related

Why does my CalcOddIntegers method always return zero?

This method is supposed to take user input for the length of the array, and then the integers that are part of the array, and return the amount of odd numbers in the array. However, it always returns zero for the count of odd integers and I am unsure as to why. The scanner is declared outside of this method.
System.out.print("Enter length of sequence\n");
int length = console.nextInt();
int[] array = new int[length];
System.out.print("Enter the sequence: \n");
int count = 0;
int i = 0;
for (i = 0; i < length; i++) {
array[i] = console.nextInt();
}
for (i = 0; i < length -1; i++); {
if (array[i] % 2 != 0) {
count++;
}
}
System.out.printf("The count of odd integers in the sequence is %d\n", count);
}
Example of console:
2. Calculate the factorial of a given number
3. Calculate the amount of odd integers in a given sequence
4. Display the leftmost digit of a given number
5. Calculate the greatest common divisor of two given integers
6. Quit
3
Enter length of sequence
4
Enter the sequence:
1
2
3
4
The count of odd integers in the sequence is 0
I have tried experimenting with the for statements with different variables to see if something was conflicting but nothing has worked.
Remove the semi-colon (;) in the line
for (i = 0; i < length -1; i++);
the semi-colon terminates the loop hence an assumption that your line does nothing.
After the second for there is a semicolon that shouldn't be there. The syntax is technically correct however, there is nothing to execute so the block that checks for odd numbers is going to be executed only once. I suggest using a debugger that will help you troubleshoot issues easier.

(Java)Why does my decimal to binary conversion method only work some of the time when counting consecutive integers in a character array?

I'm a novice Java coder working on a problem dealing with counting consecutive integers in the binary forms of numbers.
The numbers are read from the input, and converted to binary using the method called conversion. The binary form is then sent to a character array where the for loop checks for consecutive characters(specifically the number 1) and prints the maximum count as the final answer.
I've managed to get the code to a state where I feel it should be working, but I've only had success with about half of the test cases. The larger number conversions like 262,141 tend to produce incorrect answers. Can anyone tell me where I've gone wrong?
I have a suspicion that it's something to do with the character array, but after several hours of research I haven't been able to find a solution to my particular problem.
import java.io.*;
import java.util.*;
public class Solution {
public static int conversion(int decimal){//this will take the decimal from the input and convert it to binary
int result = 0;//the result from each step of the conversion
int base = 1;//used to multiply the remainder by 1, 10, 100 etc
while(decimal > 0){
int remainder = decimal % 2;//takes the remainder of the iteration
decimal = decimal / 2;//halves the decimal number
result = result + (remainder * base);//pseudo concatenation of the binary
base = base * 10;//increases the base multiplier to continue filling out the binary leftward
}
return result;//returns result after loop has finished
}
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();//scan the input to obtain the decimal number
int binaryForm = conversion(n);//convert the decimal to binary and assign to binaryForm variable
String stringForm = Integer.toString(binaryForm);//convert binaryForm to a String
int counter = 1;
int max = 1;
char testArray[] = stringForm.toCharArray();//send stringForm to fill out testArray
for(int i = 0; i < testArray.length - 1; i++){//loops through testArray to test stringForm values
if(testArray[i] == testArray[i + 1] && testArray[i] == '1'){//if consecutive values equal char 1, increase counter
counter += 1;
if(counter > max){
max = counter;//if counter is higher than current maxCounter, increase maxCounter
}
}
else {//if consecutive values do not equal 1, reset counter
counter = 1;
}
}
System.out.print(max);//print the maximum consecutive values for the decimal input when converted to binary
}
}
You are trying to create a binary representation of a decimal number using an integer. This will work for smaller numbers but it doesn't take long for you to reach an overflow. You should use a string representation of the binary number like so
String numBin = "";
while(num > 0)
{
numBin = num % 2 + numBin;
num = num / 2;
}
System.out.println("Binary Representation: " + numBin);
Then take that string and loop through it calculating the consecutive counts of 1's
int consecutiveCount = 0;
for(int i = 0; i < numBin.length() - 1; i++)
{
if(numBin.charAt(i) == '1' && numBin.charAt(i + 1) == '1')
{
consecutiveCount++;
}
}
System.out.println("Consecutive Count: " + consecutiveCount);
Output
Number: 261141
Binary Representation: 111111110000010101
Consecutive Count: 7
Number: 3
Binary Representation: 11
Consecutive Count: 1
Number: 18
Binary Representation: 10010
Consecutive Count: 0
Number: 1111111
Binary Representation: 100001111010001000111
Consecutive Count: 5

Processing numbers program

Firstly, I'm taking AP Computer Science this year, and this question is related to an exercise we were assigned in class. I have written the code, and verified that it meets the requirements to my knowledge, so this is not a topic searching for homework answers.
What I'm looking for is to see if there's a much simpler way to do this, or if there's anything I could improve on in writing my code. Any tips would be greatly appreciated, specific questions asked below the code.
The exercise is as follows: Write a program called ProcessingNumbers that does:
Accepts a user input as a string of numbers
Prints the smallest and largest of all the numbers supplied by the user
Print the sum of all the even numbers the user typed, along with the largest even number typed.
Here is the code:
import java.util.*;
public class ProcessingNumbers {
public static void main(String[] args) {
// Initialize variables and objects
Scanner sc = new Scanner(System.in);
ArrayList<Integer> al = new ArrayList();
int sumOfEven = 0;
// Initial input
System.out.print("Please input 10 integers, separated by spaces.");
// Stores 10 values from the scanner in the ArrayList
for(int i = 0; i < 10; i++) {
al.add(sc.nextInt());
}
// Sorts in ascending order
Collections.sort(al);
// Smallest and largest values section
int smallest = al.get(0);
int largest = al.get(al.size() - 1);
System.out.println("Your smallest value is " + smallest + " and your largest value is " + largest);
// Sum of Even numbers
int arrayLength = al.size();
for (int i = 0; i < al.size(); i++) {
if (al.get(i) % 2 == 0) {
sumOfEven += al.get(i);
}
}
System.out.println("The sum of all even numbers is " + sumOfEven);
// Last section, greatest even number
if (al.get(arrayLength - 1) % 2 == 0) {
System.out.println("The greatest even number typed is " + al.get(arrayLength - 1));
} else {
System.out.println("The greatest even number typed is " + al.get(arrayLength - 2));
}
sc.close();
}
}
Here are specific questions I'd like answered, if possible:
Did I overthink this? Was there a much simpler, more streamlined way to solve the problem?
Was the use of an ArrayList mostly necessary? We haven't learned about them yet, I did get approval from my teacher to use them though.
How could I possibly code it so that there is no 10 integer limit?
This is my first time on Stackoverflow in quite some time, so let me know if anything's out of order.
Any advice is appreciated. Thanks!
Usage of the ArrayList wasn't necessary, however it does make it much simpler due to Collections.sort().
To remove the 10 integer limit you can ask the user how many numbers they want to enter:
int numbersToEnter = sc.nextInt();
for(int i = 0; i < numbersToEnter; i++) {
al.add(sc.nextInt());
}
Another note is that your last if-else to get the highest even integer doesn't work, you want to use a for loop, something like this:
for (int i = al.size() - 1; i >= 0; i--) {
if (al.get(i) % 2 == 0) {
System.out.println("The greatest even number typed is " + al.get(i));
break;
}
I wouldn't say so. Your code is pretty straightforward and simple. You could break it up into separate methods to make it cleaner and more organized, though that isn't necessary unless you have sections of code that have to be run repeatedly or if you have long sections of code cluttering up your main method. You also could have just used al.size() instead of creating arrayLength.
It wasn't entirely necessary, though it is convenient. Now, regarding your next question, you definitely do want to use an ArrayList rather than a regular array if you want it to have a variable size, since arrays are created with a fixed size which can't be changed.
Here's an example:
int number;
System.out.print("Please input some integers, separated by spaces, followed by -1.");
number = sc.nextInt();
while (number != -1) {
al.add(number);
number = sc.nextInt();
}
Here is a solution that:
Doesn't use Scanner (it's a heavyweight when all you need is a line of text)
Doesn't have a strict limit to the number of numbers
Doesn't need to ask how many numbers
Doesn't waste space/time on a List
Handles the case when no numbers are entered
Handles the case when no even numbers are entered
Fails with NumberFormatException if non-integer is entered
Moved actual logic to separate method, so it can be mass tested
public static void main(String[] args) throws Exception {
System.out.println("Enter numbers, separated by spaces:");
processNumbers(new BufferedReader(new InputStreamReader(System.in)).readLine());
}
public static void processNumbers(String numbers) {
int min = 0, max = 0, sumOfEven = 0, maxEven = 1, count = 0;
if (! numbers.trim().isEmpty())
for (String value : numbers.trim().split("\\s+")) {
int number = Integer.parseInt(value);
if (count++ == 0)
min = max = number;
else if (number < min)
min = number;
else if (number > max)
max = number;
if ((number & 1) == 0) {
sumOfEven += number;
if (maxEven == 1 || number > maxEven)
maxEven = number;
}
}
if (count == 0)
System.out.println("No numbers entered");
else {
System.out.println("Smallest number: " + min);
System.out.println("Largest number: " + max);
if (maxEven == 1)
System.out.println("No even numbers entered");
else {
System.out.println("Sum of even numbers: " + sumOfEven);
System.out.println("Largest even number: " + maxEven);
}
}
}
Tests
Enter numbers, separated by spaces:
1 2 3 4 5 6 7 8 9 9
Smallest number: 1
Largest number: 9
Sum of even numbers: 20
Largest even number: 8
Enter numbers, separated by spaces:
1 3 5 7 9
Smallest number: 1
Largest number: 9
No even numbers entered
Enter numbers, separated by spaces:
-9 -8 -7 -6 -5 -4
Smallest number: -9
Largest number: -4
Sum of even numbers: -18
Largest even number: -4
Enter numbers, separated by spaces:
No numbers entered

How to use something like the charAt for integers

I am trying to make a program that uses three digit numbers to identify items and I am trying to use something like the charAt method for integers or something. Im not too sure. Im a beginner and I apologize i just need help. Also I need a bit of help to use an if statement and relational operators. Im trying to do if the last digit in the number is less than 5 then it is {item} and if its greater than 5 then its this {item}. Something like that. Thank you so much in advance.
String number;
System.out.println("Enter three digit number: ");
number = in.nextLine();
switch (number.charAt(0))
{
//stuff
}
if (number > 5)
{
//it is this item
{
else
{
//it is the other item
{
There are at least two ways you can do it:
String number = in.nextLine();
char c = number.charAt(i); // i is the position of digit you want to retrieve
int digit = c - '0';
if you want to get ith digit from the end of an Integer, do:
int digit = 0;
while(i > 0) {
digit = n%10;
n /= 10;
--i;
}
To check the last digit of a base-10 number, use the remainder operator:
if (number % 10 < 5) {
// handle last digit is 0-4
} else {
// handle last digit is 5-9
}

I need to separate a integer then add the digits together in java

Good morning, I am on now to lesson 4 and am having a bit of trouble using loops. Please note that I have seen it resolved using strings but I am trying to grasp loops.
The reason for the trouble is I need to show both answers: The integer broken into individual number ex: 567 = 5 6 7
And then 567 = 18
I am able to get the integer added together but am not sure on how to separate the integer first and then add the individual numbers together. I am thinking that I need to divide down to get to 0. For instance if its a 5 digit number /10000, /1000, /100, /10, /1
But what if the user wants to do a 6 or 7 or even a 8 digit number?
Also I am assuming this would have to be first and then the addition of the individual integers would take place?
thanks for the guidance:
import java.util.Scanner;
public class spacing {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n;
System.out.print("Enter a your number: ");
n = in.nextInt();
int sum = 0;
while (n != 0) {
sum += n % 10;
n /= 10;
}
System.out.println("Sum: " + sum);
}
}
Since this is a lesson, I won't give you the solution outright, but I will give you some hints:
You're only thinking in int. Think in String instead. :) This will also take care of the case where users provide you numbers with a large number of digits.
You will need to validate your input though; what if someone enters "12abc3"?
String.charAt(int) will be helpful.
Integer.parseInt(String) will also be helpful.
You could also look at using long instead of int; long has an upper limit of 9,223,372,036,854,775,807 though.
//I assume that the input is a string which contains only digits
public static int parseString(String input)
{
char[] charArray = input.toCharArray();
int sum = 0;
for (int index = 0; index < input.length; index++)
{
sum += Integer.parseInt(charArray[index] + "");
}
return sum;
}
Use the function above, pass your input to the function and use the output as you like.

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