I'm trying to simulate rolling a die 100 times, and printing the results of how many 1/2/3/4/5/6 i landed. Here's my code thus far: I'm trying to use a while loop for my assignment, and i need to use (Math.random( )*6 + 1) to generate numbers.
public class RollingDice {
public static void main(String args[]) {
int count = 0; // number of times die was rolled
int count1s = 0; // number of times 1 was rolled
int count2s = 0; // number of times 2 was rolled
int count3s = 0;
int count4s = 0;
int count5s = 0;
int count6s = 0;
while (count < 100) {
count1s = (int) (Math.random( )*6 + 1);
count2s = (int) (Math.random( )*6 + 1);
count3s = (int) (Math.random( )*6 + 1);
count4s = (int) (Math.random( )*6 + 1);
count5s = (int) (Math.random( )*6 + 1);
count6s = (int) (Math.random( )*6 + 1);
count++;
}
System.out.println("Number of times the die was rolled: "+ count);
System.out.println("Number of times 1 was rolled: " + count1s);
System.out.println("Number of times 2 was rolled: " + count2s);
System.out.println("Number of times 3 was rolled: " + count3s);
System.out.println("Number of times 4 was rolled: " + count4s);
System.out.println("Number of times 5 was rolled: " + count5s);
System.out.println("Number of times 6 was rolled: " + count6s);
}
}
My code currently prints:
Number of times the die was rolled: 100
Number of times 1 was rolled: 3
Number of times 2 was rolled: 1
Number of times 3 was rolled: 5
Number of times 4 was rolled: 2
Number of times 5 was rolled: 4
Number of times 6 was rolled: 4
As you can see, its rolling 100 times, but its only saving the results of 1 roll, not 100, How do I fix this?
On each iteration of your while loop, you are reassigning the value of count1s, count2s, and the others. Instead what you should do is you should "roll the dice" and then see what value it is, and increment the proper variable.
while (count < 100) {
int diceRoll = (int) (Math.random() * 6 + 1);
if (diceRoll == 1)
count1s++;
else if (diceRoll == 2)
count2s++;
// ... you get the idea
count++;
}
And as a fun sidenote, using Java 8 there is a significantly easier, and more cool way to do this.
Stream.generate(() -> (int) (Math.random() * 6 + 1))
.limit(100L)
.collect(Collectors.groupingBy(num -> num,
Collectors.counting()))
.forEach((num, count) -> System.out.println("number of times " + num + " was rolled: " + count));
Each iteration you are replacing the previous roll's data.You can rewrite the logic as
// initialization
while(count < 100){
int currentRoll = (int) (Math.random() * 6 + 1);
if(currentRoll == 1)
count1s++;
// Same logic for all occurances
}
Because your logic is incorrect.
Inside while loop, you assigned appearance time of each roll with value of dice.
=> Counter of each always < 7.
Also, each time your call Math.random() will give you new value => Should call it once each roll.
In this case, use switch - case statement will be correct.
while (count < 100) {
int num = (int) (Math.random( )*6 + 1);
switch(num) {
case 1:
count1s++;
break;
case 2:
count2s++;
break;
case 3:
count3s++;
break;
case 4:
count4s++;
break;
case 5:
count5s++;
break;
case 6:
count6s++;
break;
}
count++;
}
Related
I am practicing Java and I was trying to create a program to calculate the amount of ways an number could be divided using a set number of dividers.
For instance:
100 is the number and the dividers are 50,20,5. What are the possible divisions.
The answer would be:
Amount of 50 : 0, Amount of 20 : 0, Amount of 10 : 10
Amount of 50 : 0, Amount of 20 : 1, Amount of 10 : 8
Amount of 50 : 0, Amount of 20 : 2, Amount of 10 : 6
Amount of 50 : 0, Amount of 20 : 3, Amount of 10 : 4
Amount of 50 : 0, Amount of 20 : 4, Amount of 10 : 2
Amount of 50 : 1, Amount of 20 : 0, Amount of 10 : 5
Amount of 50 : 1, Amount of 20 : 1, Amount of 10 : 3
Amount of 50 : 1, Amount of 20 : 2, Amount of 10 : 1
Amount of 50 : 2
I wrote a code that asks the user an amount and 3 dividers. Now I am trying to figure out if there is a way to dynamically create a code for as many dividers as the user wants. The code is in a way very repetitive and there is a certain pattern to add another divider but I cannot figure out how to implement this dynamic change to the code.
The first code I came up with to do this is the following:
public class Test2 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Insert the amount:");
int amount = scanner.nextInt();
List<Integer> dividers = new ArrayList<>();
System.out.println("Insert the first divider:");
int tempDivider = scanner.nextInt();
if (!dividers.contains(tempDivider)) {
dividers.add(tempDivider);
}
while (dividers.size()<3) {
System.out.println("Insert the next divider: (" + (3-dividers.size()) + " more to go)");
tempDivider = scanner.nextInt();
if (!dividers.contains(tempDivider)) {
dividers.add(tempDivider);
}
}
dividers.sort(Collections.reverseOrder());
System.out.print("Dividers are: ");
System.out.println(dividers);
int getal1 = dividers.get(0);
int getal2 = dividers.get(1);
int getal3 = dividers.get(2);
int fiftyAmount = amount / getal1;
int fiftyRemainder = amount % getal1;
for (int i = 0; i <= fiftyAmount; i++) {
int currentFiftyAmount = amount - (getal1 * i);
int twentyAmount = currentFiftyAmount / getal2;
int twentyRemainder = currentFiftyAmount % getal2;
if (twentyAmount == 0) {
StringBuilder output = new StringBuilder();
output.append("Amount of " + getal1 + " banknotes: " + i);
if (fiftyRemainder != 0) output.append(", Remainder: " + fiftyRemainder);
System.out.println(output);
} else {
for (int j = 0; j <= twentyAmount; j++) {
int currentTwentyAmount = currentFiftyAmount - (getal2 * j);
int tenAmount = currentTwentyAmount / getal3;
int tenRemainder = currentTwentyAmount % getal3;
if (tenAmount == 0) {
StringBuilder output = new StringBuilder();
output.append("Amount of " + getal1 + " banknotes: " + i + ", Amount of " + getal2 + " banknotes: " + j);
if (tenRemainder != 0) output.append(", Remainder: " + twentyRemainder);
} else {
StringBuilder output = new StringBuilder();
output.append("Amount of " + getal1 + " banknotes: " + i + ", Amount of " + getal2 + " banknotes: " + j +
", Amount of " + getal3 + " banknotes: " + tenAmount);
if (tenRemainder != 0) output.append(", Remainder: " + tenRemainder);
System.out.println(output);
}
}
}
}
}
}
I tried to make this more abstract to figure out a way to automate the creation of the extra dividing loops but I cannot figure it out.
The more abstract version I wrote is the following:
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Insert the amount:");
int amount = scanner.nextInt();
List<Integer> dividers = new ArrayList<>();
System.out.println("Insert the first divider:");
dividers.add(scanner.nextInt());
int divider;
while (dividers.size()<2) {
System.out.println("Insert the next divider: (" + (2-dividers.size()) + " more to go)");
divider = scanner.nextInt();
if (!dividers.contains(divider)) {
dividers.add(divider);
}
}
dividers.sort(Collections.reverseOrder());
System.out.print("Dividers are: ");
System.out.println(dividers);
int divided1Amount = amount / dividers.get(0);
int divided1Remainder = amount % dividers.get(0);
for (int i = 0; i <= divided1Amount; i++) {
int currentDivided1Amount = amount - (dividers.get(0) * i);
int divided2Amount = currentDivided1Amount / dividers.get(1);
int divided2Remainder = currentDivided1Amount % dividers.get(1);
if (divided2Amount == 0) {
StringBuilder output = new StringBuilder();
output.append(dividers.get(0) + ":" + i);
if (divided1Remainder != 0) {
output.append(", Remainder: " + divided1Remainder);
}
System.out.println(output);
} else {
StringBuilder output = new StringBuilder();
output.append(dividers.get(0) + ":" + i + "," + dividers.get(1) + ":" + divided2Amount);
if (divided2Remainder != 0) {
output.append(", Remainder: " + divided2Remainder);
}
System.out.println(output);
}
}
}
}
This is also available on GitHub: https://github.com/realm1930/rekendin/blob/master/src/Main.java
Could anybody please enlighten me. I am sorry if I am not clear at my description of the issue.
Thanks
While a fixed number of dividers can be well approached with nested loops, I suggest for the general case to write the solution as a recursive function.
This problem is a good fit for dynamic programming. What I mean by this is that the problem can be broken down into simpler subproblems, and in this way the solution is naturally implemented with recursion. For instance, in your example of expressing 100 as a sum of multiples of 50, 20, and 10, there are three solutions found that all use one 50:
Amount of 50 : 1, Amount of 20 : 0, Amount of 10 : 5
Amount of 50 : 1, Amount of 20 : 1, Amount of 10 : 3
Amount of 50 : 1, Amount of 20 : 2, Amount of 10 : 1
Look at this as solving the subproblem of finding the ways that value 50 can be expressed as multiples of 20 and 10 (that is, 50 is equal to 20*0 + 10*5, 20*1 + 10*3 and 20*2 + 10*1). So you can divide-and-conquer the original problem in this sense.
Let X be the number (e.g. 100) to express, and D1, D2, ... DN the dividers. Here is a possible outline:
If there is just one divider, N = 1, it is easy: there just zero or one solution depending on whether D1 divides X.
Otherwise, possible solutions might have D1 with any multiple from 0, 1, ..., X/D1. So make a loop m1 = 0, 1, ..., X/D1, and recursively solve the subproblem having X' = X - m1*D1 and the remaining dividers D2, ..., DN. This subproblem has one fewer divider, so after enough recursions it reduces to the N = 1 case.
That solves the problem. Note, though, that fully recursing may result in a combinatorially vast number of subproblems to solve. So for efficient solution it is a good idea to store or "memoize" the solutions of previously-solved subproblems in a table so that work isn't repeated.
Other thoughts:
Let Q be the greatest common divisor (GCD) of all the dividers {D1, ..., DN}. If X isn't divisible by Q, then there are no solutions, in which case we can skip the above recursive search entirely. E.g. there is no way to express X = 103 with dividers 50, 20, and 10. This GCD test can also be applied to every subproblem so that some recursive calls can return early.
This problem is a kind of Diophantine equation, more specifically, it is related to the Frobenius coin problem and Frobenius numbers. There is a mathoverflow post discussing it.
I'm trying to create a counter controlled while loop. Currently I'm having difficulty getting the counter to increase by 1 for each pass through off the loop.
I set my code to
int numberCounter = 0; // Numbers 0 through 10.
String head1 = "Number: " + numberCounter;
String head2 = " Multiplied by 2: " + numberCounter * 2;
String head3 = " Multiplied by 10: " + numberCounter * 10;
int byTwo; // Stores the number multiplied by 2.
int byTen; // Stores the number multiplied by 10.
final int NUM_LOOPS = 11; // Constant used to control loop.
// This is the work done in the housekeeping() method
System.out.println("Numbers 0 through 10 multiplied by 2 and by 10" + "\n");
System.out.println(head1 + head2 + "\n");
System.out.println(head1 + head3 + "\n");
while (numberCounter != 10) numberCounter = numberCounter + 1;
System.out.println(head1 + head2 + "\n");
System.out.println(head1 + head3 + "\n");
but it just reads the 0 value and exits after one pass.
I expect each pass to add one to the counter, but it seems to stay at 0. I say that because the output reads:
Numbers 0 through 10 multiplied by 2 and by 10
Number: 0 Multiplied by 2: 0
Number: 0 Multiplied by 10: 0
Number: 0 Multiplied by 2: 0
Number: 0 Multiplied by 10: 0
as mentioned in the comments, make sure your counter variable starts from 0 :
int numberCounter = 0;
while (numberCounter != 10) {
System.out.println(numberCounter);
numberCounter = numberCounter + 1; // or numberCounter++;
}
UPDATE
After you posted your full code, it seems clear that you expect that each iteration of your integer would change the value assigned to your Strings, eg head2 & head3. This is wrong. At the point you initialized these String variables your integer was converted to a String inside that variable (since you used string concatenation). To see the effect of the iterated integer, you can add the below println statements inside your loop, eg :
while (numberCounter != 10) {
numberCounter = numberCounter + 1;
System.out.println(" Multiplied by 2: " + numberCounter * 2);
System.out.println(" Multiplied by 10: " + numberCounter * 10);
}
I need to print the factors of a perfect number. Here's the gist of my main class:
ArrayList<Integer> perfNums = new ArrayList<>();
Scanner in = new Scanner(System.in);
System.out.print("Enter the upperbound: ");
upperbound = in.nextInt();
for (int i = 1; i <= upperbound; i++) {
if (isPerfect(i)) { //boolean to check if number is a perfect number
perfNums.add(i);
}
}
System.out.println("Perfect numbers between 1 and " + upperbound + " are:");
for (int i = 0; i < perfNums.size(); i++) {
System.out.print(perfNums.get(i) + " = ");
printFactor((int)perfNums.get(i));
System.out.println();
}
Here's the printFactor class.
private static void printFactor(int number){
int factor = 1;
while(factor < number){
if (number%factor == 0) System.out.print(factor+ " + ");
//I don't know how to print the + sign otherwise.
factor++;
}
}
And here's a sample output:
Enter the upperbound: 10000
Perfect numbers between 1 and 10000 are:
6 = 1 + 2 + 3 +
28 = 1 + 2 + 4 + 7 + 14 +
496 = 1 + 2 + 4 + 8 + 16 + 31 + 62 + 124 + 248 +
8128 = 1 + 2 + 4 + 8 + 16 + 32 + 64 + 127 + 254 + 508 + 1016 + 2032 + 4064 +
I've got the main gist of it but I've struggled with an output issue. Due to the restrictions of my online submission system, my output needs to fit exact specifications.
My question is how do I go about printing all the factors of my perfect number but removing the + sign at the end? (e.g)6 = 1 + 2 + 3
I'm not too sure of many methods to print from a while loop. Would a for-loop be better for my goals? Or are there alternative methods to print the factors of a number?
The least amount of change to address this might be something like this:
private static void printFactor(int number)
System.out.print(1);
int factor = 2;
while (factor<number) {
if (number%factor == 0) System.out.print(" + " + factor);
factor++;
}
}
1 is always a factor, so you can print that before the loop and then prepend + to every subsequent factor.
You should cache the output you want to print into a StringBuilder. Then you are able to remove the last plus sign before you print the whole String. It also has a better performance.
private static void printFactor(int number)
{
StringBuilder output = new StringBuilder();
int factor = 1;
while (factor < number)
{
if (number % factor == 0)
output.append(factor + " + ");
factor++;
}
// remove last plus sign
output.deleteCharAt(output.length() - 1);
// print the whole string
System.out.print(output.toString());
}
Since factor starts from value 1 and number % 1 == 0 will always be true, you might print 1 first and then flip factor and + in System.out.print. Like this:
private static void printFactor(int number) {
if(number > 0) {
System.out.print(1);
}
int factor = 2;
while (factor<number) {
if (number % factor == 0) {
System.out.print(" + " + factor);
}
factor++;
}
}
Not the best solution, but it will do the job.
Try to create a variable String numb and use substring method like this:
String numb ="";
while(factor<number){
if(number%factor == 0)
numb= numb + factor+ " + ";
factor++;
}
System.out.print(numb.substring(0, numb.trim().length()-1));
Just for the sake of using Java 8 :)
private static void printFactor(int number){
System.out.println(IntStream.range(1, number)
.filter(p -> number % p == 0)
.mapToObj(i -> String.valueOf(i))
.collect(Collectors.joining(" + ")));
}
Thanks everyone for the quick response. You all have been a lifesaver, and I managed to pick up some new things to consider when I code in the future.
Anyway, while waiting for a reply I was fiddling with the code and came up with a rather inelegant solution, if anybody's interested. Here's the changes to the main class:
System.out.println("Perfect numbers between 1 and " + upperbound + " are:");
for(int i=0; i<perfNums.size(); i++){
System.out.print(perfNums.get(i) + " = ");
outputString = printFactor2(perfNums.get(i));
if(outStr.endsWith(" + ")) outStr = outStr.substring(0, outStr.length()-3);
//because the submission system would cry foul with even a single extra space
System.out.println(outStr);
}
And here's the changes to the printFactor class:
private static String printFactor2(int number){
String out = "";
int factor = 1;
while(factor<number){
if(number%factor == 0) out += factor + " + ";
factor++;
}
return out;
}
Basically, what I did was append the factors to a string, then removing the trailing + sign using the substring method. On hindsight, I probably should've called the substring method inside the printFactor class instead. Something like return out.substring(0, out.length()-3); perhaps?
Nevertheless, thanks everyone!
I have been trying to find where the error is in this code for some time now and I just can't figure it out. The program is rolling a 6 sided die 300 times, and then outputting the number of time each number is rolled. But for some reason, rather than rolling it 300 times, it's rolling 320 times. I don't see anything wrong with the for-loop so I'm really at a loss here.
public static void dieRoll(){
int[] roll = new int [300];
int[] count = new int[] {1,2,3,4,5,6};
for(int i = 1; i<300; i++){
roll[i] = (int) Math.ceil( (int) (Math.random()*6)+1 );
// roll[i] = (int) Math.ceil(roll[i]);
// System.out.println(roll[i]);
if(roll[i]==1){
count[0]++;
}
else if(roll[i]==2){
count[1]++;
}
else if(roll[i]==3){
count[2]++;
}
else if(roll[i]==4){
count[3]++;
}
else if(roll[i]==5){
count[4]++;
}
else if(roll[i]==6){
count[5]++;
}
// System.out.println(roll[i]);
}//i loop
System.out.println("The die landed on 1 " + count[0] + " times.");
System.out.println("The die landed on 2 " + count[1] + " times.");
System.out.println("The die landed on 3 " + count[2] + " times.");
System.out.println("The die landed on 4 " + count[3] + " times.");
System.out.println("The die landed on 5 " + count[4] + " times.");
System.out.println("The die landed on 6 " + count[5] + " times.");
System.out.println("The die was rolled this many times: " + (count[0]+count[1]+count[2]+count[3]+count[4]+count[5]));
}//dieRoll()
If someone could just please point me out to where the error might be manifesting itself, that would be awesome. Thank you.
You initialised your counts like this:
int[] count = new int[] {1,2,3,4,5,6};
Now, 1 + 2 + 3 + 4 + 5 + 6 is equal to 21. Your loop goes from 1 to 299, which is 299 iterations. And of course, 299 + 21 is 320.
You should initialise your array to all zeros.
Finally, your code can be simplified:
for( int i = 0; i < 300; i++ )
{
roll[i] = (int) Math.ceil( (int) (Math.random()*6)+1 );
count[roll[i] - 1]++;
}
I have a class question that I cannot seem to understand the logic for.
Modify the program below to print a histogram in which the total number of times the dice rolls equals each possible value is displayed by printing a character like * that number of times, as shown below.
Histogram showing total number of dice rolls for each possible value.
Dice roll histogram:
2: ******
3: ****
4: ***
5: ********
6: *******************
7: *************
8: *************
9: **************
10: ***********
11: *****
12: ****
I do not understand what in the world this histogram is displaying. Its driving me insane and I cannot move forward with my logic if I do not understand what I am doing. I know this question has been asked before but it looks like they all have a specific number of dice roles they are going off of. I am not given a number and this is what is throwing me off. I know this is really a stupid question. But can anyone possibly explain to me what they mean by "Histogram showing total number of dice rolls for each possible value" what is defining this possible value? I am at a total loss... Any help is appreciated. Here is the code I have written so far.
import java.util.Scanner;
import java.util.Random;
public class DiceStats {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
Random randGen = new Random();
int i = 0; // Loop counter iterates numRolls times
int numRolls = 0; // User defined number of rolls
int numOnes = 0; // Tracks number of 1's found
int numTwos = 0; // Tracks number of 2's found
int numThrees = 0; // Tracks number of 3's found
int numFours = 0; // Tracks number of 4's found
int numFives = 0; // Tracks number of 5's found
int numSixes = 0; // Tracks number of 6's found
int numSevens = 0; // Tracks number of 7's found
int numEights = 0; // Tracks number of 8's found
int numNines = 0; // Tracks number of 9's found
int numTens = 0; // Tracks number of 10's found
int numElevens = 0; // Tracks number of 11's found
int numTwelves = 0; // Tracks number of 12's found
int die1 = 0; // Dice values
int die2 = 0; // Dice values
int rollTotal = 0; // Sum of dice values
System.out.println("Enter number of rolls: ");
numRolls = scnr.nextInt();
if (numRolls >= 1) {
// Roll dice numRoll times
for (i = 0; i < numRolls; ++i) {
die1 = randGen.nextInt(6) + 1;
die2 = randGen.nextInt(6) + 1;
rollTotal = die1 + die2;
// Count number of sixes and sevens
if (rollTotal == 1) {
numOnes = numOnes + 1;
}
if (rollTotal == 2) {
numTwos = numTwos + 1;
}
if (rollTotal == 3) {
numThrees = numThrees + 1;
}
if (rollTotal == 4) {
numFours = numFours + 1;
}
if (rollTotal == 5) {
numFives = numFives + 1;
}
if (rollTotal == 6) {
numSixes = numSixes + 1;
}
if (rollTotal == 7) {
numSevens = numSevens + 1;
}
if (rollTotal == 8) {
numEights = numEights + 1;
}
if (rollTotal == 9) {
numNines = numNines + 1;
}
if (rollTotal == 10) {
numTens = numTens + 1;
}
if (rollTotal == 11) {
numElevens = numElevens + 1;
}
else if (rollTotal == 12) {
numTwelves = numTwelves + 1;
}
System.out.println("Roll " + (i+1) + " is " + rollTotal + " (" + die1 +
"+" + die2 + ")");
}
// Prints a histogram of the number of dice rolls
System.out.println("\nDice roll histogram:");
System.out.println("1's: " + numOnes);
System.out.println("2's: " + numTwos);
System.out.println("3's: " + numThrees);
System.out.println("4's: " + numFours);
System.out.println("5's: " + numFives);
System.out.println("6's: " + numSixes);
System.out.println("7's: " + numSevens);
System.out.println("8's: " + numEights);
System.out.println("9's: " + numNines);
System.out.println("10's: " + numTens);
System.out.println("11's: " + numElevens);
System.out.println("12's: " + numTwelves);
}
else {
System.out.println("Invalid rolls. Try again.");
}
return;
}
}
You can see where I entered the entry for histograms. I basically thought that I needed to edit my value given from the integers such as "numOnes" to asterisk but now I'm not certain... any help is appreciated!
EDITED CODE -
System.out.println("\nDice roll histogram:");
System.out.print("2's: ");
for(i = 0; i < numTwos; i++){
System.out.print("*");
}
System.out.println("");
System.out.print("3's: ");
for (i = 0; i < numThrees; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("4's: " );
for (i = 0; i < numFours; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("5's: ");
for (i = 0; i < numFives; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("6's: ");
for (i = 0; i < numSixes; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("7's: ");
for (i = 0; i < numSevens; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("8's: ");
for (i = 0; i < numEights; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("9's: ");
for (i = 0; i < numNines; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("10's: ");
for (i = 0; i < numTens; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("11's: ");
for (i = 0; i < numElevens; i++);{
System.out.print("*");
}
System.out.println("");
System.out.print("12's: ");
for (i = 0; i < numTwelves; i++);{
System.out.print("*");
}
System.out.println("");
}
OUTPUTS -
Enter number of rolls:
5
Roll 1 is 8 (2+6)
Roll 2 is 9 (6+3)
Roll 3 is 9 (5+4)
Roll 4 is 6 (4+2)
Roll 5 is 9 (6+3)
Dice roll histogram:
2's:
3's: *
4's: *
5's: *
6's: *
7's: *
8's: *
9's: *
10's: *
11's: *
12's: *
I can enter a larger number of rolls and I will get an asterisk for the 2's and it will increase like I need but it will not increase the rest of the numbers and they all only get one asterisk. What is keeping my code from properly increasing the amount of *'s? Iv been fighting with this for hours :/
"I do not understand what in the world this histogram is displaying."
Well, as you said:
"Histogram showing total number of dice rolls for each possible value"
The histogram:
2: ******
3: ****
4: ***
5: ********
6: *******************
7: *************
8: *************
9: **************
10: ***********
11: *****
12: ****
is a record of the rolls of a pair of six sided dice. The possible values of totaling a pair of dice range from 2 to 12. If you rolled them 100 times they might give these results.
This histogram shows that the value 6 was most frequently rolled (19 times) and 4 the least frequently rolled (3 times). If you counted up every * you'd know how many times the dice have been rolled.
You may think that a histogram must look like this:
But turn that sideways:
and imagine that the blue bars are *'s, the 100 - 150 label is a 2, and the 150 - 200 label is a 3, well then it starts to look like your histogram.
Either form is a histogram. They let you compare quantities (how many) of things that fall in different categories (kinds) of things.
A graphic chart is difficult to output from a program that is text based so instead it's asking you to display what is basicly ascii art:
If this was in a text file, and not program output, this could also be considered a form of tally. You can easily add new *'s as you receive new data. It's the same trick as this:
Hope that makes more sense.
SPOILER ALERT: If that helped and you'd like to take a crack at modifying the program yourself read no further. Otherwise...
This
System.out.println("\nDice roll histogram:");
System.out.println(" 1's: " + nManyStars(numOnes));
System.out.println(" 2's: " + nManyStars(numTwos));
System.out.println(" 3's: " + nManyStars(numThrees));
System.out.println(" 4's: " + nManyStars(numFours));
System.out.println(" 5's: " + nManyStars(numFives));
System.out.println(" 6's: " + nManyStars(numSixes));
System.out.println(" 7's: " + nManyStars(numSevens));
System.out.println(" 8's: " + nManyStars(numEights));
System.out.println(" 9's: " + nManyStars(numNines));
System.out.println("10's: " + nManyStars(numTens));
System.out.println("11's: " + nManyStars(numElevens));
System.out.println("12's: " + nManyStars(numTwelves));
and this
static String nManyStarsOld(int n) {
String result = "";
for (int i = 0; i < n; i++) {
result += "*";
}
return result;
}
should, if dropped in the right places, get your program to stop printing what it prints now which is this:
Enter number of rolls:
20
Roll 1 is 5 (2+3)
Roll 2 is 10 (4+6)
Roll 3 is 7 (5+2)
Roll 4 is 7 (5+2)
Roll 5 is 5 (1+4)
Roll 6 is 11 (6+5)
Roll 7 is 8 (3+5)
Roll 8 is 8 (2+6)
Roll 9 is 7 (1+6)
Roll 10 is 8 (3+5)
Roll 11 is 12 (6+6)
Roll 12 is 6 (2+4)
Roll 13 is 8 (6+2)
Roll 14 is 8 (4+4)
Roll 15 is 7 (1+6)
Roll 16 is 4 (2+2)
Roll 17 is 6 (5+1)
Roll 18 is 7 (6+1)
Roll 19 is 6 (1+5)
Roll 20 is 5 (1+4)
Dice roll histogram:
1's: 0
2's: 0
3's: 0
4's: 1
5's: 3
6's: 3
7's: 5
8's: 5
9's: 0
10's: 1
11's: 1
12's: 1
And instead, get it to print this:
Dice roll histogram:
1's:
2's:
3's:
4's: *
5's: ***
6's: ***
7's: *****
8's: *****
9's:
10's: *
11's: *
12's: *
Next time you post a question please include the current output along with the expected output.
If you feel like being a smarty pants there is actually a one line version of nManyStars():
static String nManyStars(int n) {
return new String(new char[n]).replace("\0", "*");
}
Inspired by this: https://stackoverflow.com/a/4903603/1493294
Also, if you have at least Java 11 you can trade in nManyStars(n) for "*".repeat(n)
Hope it helps
Iv got it all working. Thank you #CandiedOrange and #MadProgrammer for the help and guidance! Found that my histogram code was messed up with my for statements having a ; in an incorrect spot causing my for statement to not apply the * based on its process of running through the for statement and it was just printing a * as a normal print function. All is well. Thanks for all the help!