Thread: Help With Java Homework: Set Operations

I am not doing that well in my Java Programming class. My next assignment seems pretty simple but I have no idea of what to do and where to start. Any algorithm or sample program would be very helpful.





You will write a program called Sets.java that will:

* Read two sets of numbers from the keyboard.
* Print the intersection of the two sets, in any order, without duplicates.
* Print the union of the two sets, in any order, without duplicates.

Sample Run #1

Just for illustration, what you type looks like this:

Enter values for first set, ending with -1
1 3 9 7 5 -1
Enter values for second set, ending with -1
2 3 5 7 -1
Intersection: 3 7 5
Union: 1 3 9 7 5 2


Again any help would be very helpful. Thanks

Ok I think I'm getting there. I'm having trouble getting the Union of both sets without repeating numbers. And I have no idea how to get the intersect. I think I need to use Char.At or something and compare all the ints in both sets and only print the ones that appear in both. But im not sure how to go about it... This is what I have so far. Any help? Thanks.



package Sets;

import java.util.Scanner;

public class Sets {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);
String s = new String();
String r = new String();

System.out.println("Enter TWO numbers to begin.");
int set1 = in.nextInt();
int set2 = in.nextInt();

System.out.println("Enter values for first set, ending with -1");

while (set1 != -1){
set1 = in.nextInt();
if (set1 != -1)
s = s + set1 + " ";
}


System.out.println("Enter values for second set, ending with -1");

while (set2 != -1){
set2 = in.nextInt();
if (set2 != -1)
r = r + set2 + " ";

}


System.out.println("Union: " +s +r);

}


}

1. Code tags please.
2. Indentation please.
3. So, now you have all integers as a string concatenated to each other. You can simply extract individual integer and compare it with the other string, and then perform your task.

Thats the part im having trouble with.

If you are separating each integer into a string with any special character then you may simply use nextInt() of Scanner (util.java).

I thought I already did that to read numbers from the keyboard and stored those numbers into a string. I was kinda hoping if someone could add to my code because I literally think I do not have the java knowledge on coding this next piece and I can review and fiddle with it to see exactly what it does and how it works.

I can understand that how much problems are there for newbie. But you need to get rid of these troubles by browsing, learning, making mistakes and then you will be able to learn.

1. Initialize your string with null.
2. After getting first input and coming inside the loop, first change your integer to string and then get the other value and continue concatnating till the end.
3. As soon as you completed concatenation, you can use hasNextInt() that will extract the integer and places the pointer to that location.
4. That's how you can extract integer from strings and i hope you can compare these to eachother then.

alright. thx