Iterative Help

Im writing a program that takes a number inputed and prints the first n positive numbers beginning at 0 by 10's, separated by spaces.

For example: n=4 prints 0, n=65 prints 0 10 20 30 40 50 60

Im not understanding how to write this using an iterative method. Any help please?

First you probably want to divide the number by 10, which will give you a number that tells you how many you gotta print. for instance, 76 / 10 = 7. Then toss that into a loop which starts at 0 and goes until your integer, multiplying each by 10 and displaying it.

That makes a lot of sense, thank you.

What about recursively?

Recursively in pseudo-code:

Code java:

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public void printVals(int max, int current){
    //evaluate whether to return. Is current > max?
    //do work - increment and print
    //loop by calling myself with new values determined from work
}

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I ran into a problem with my code. My Iterative works but my Recursion isnt.

Code :

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public static int Recursion(int n) {
		int result = 1, num;
 
		num = n/10;
 
		if(n == 0) {
			result = 1; // Base case
		}
		else if(n == 1) {
			result = 1; // Base case
		}
		else {
			result = n * 10;
		}
		System.out.print("Recursive: " + result + " " + "\n");
		return result;
	}
 
	public static void Iterative(int n) {
		int var, num;
 
		var = n/10;
 
		for(int i = 0; i <= var;i++) {
			num = i*10;
			System.out.print("Iterative: " + num + " ");
		}
 
	}

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The recursive method should print the same output as the iterative method

Recursive functions call themselves...I don't see where your Recursion() function does this.

Oh, i forgot about that


but now that i tried incorporating the call it still doesnt work.

Code :

---

public static int Recursion(int n) {
		int result = 1, num;
 
		num = n/10;
 
		System.out.print("\nRecursive: ");
		if(n == 0) {
			result = 1; // Base case
		}
		else if(n == 1) {
			result = 1; // Base case
		}
		else {
			result = num * Recursion(num - 1);
		}
		System.out.print(result + " ");
		return result;
	}

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please define doesn't work...eg output, exceptions, compile time errors, etc..

My Recursive output needs to be the same as my iterative Output, but it isnt outputting the same way.

Is the parameter to Recusion() on each iteration what you would expect? Add a println in the function to test the value of the parameter to make sure it is what it should be.

I dont understand what you mean

I also need to do these but dont understand the question

Quote:

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3. Write an iterative Java method that is passed two non–negative integer numbers m and n as parameters,
and multiplies the two numbers by consecutive additions. The method should return the product m∗n.
4. Write the same method as above, but use recursion instead of iteration.

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and finally:

Quote:

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Write a recursive method to solve Ackermann’s Function assuming non–negative integers as input. Ackermann’s function is a that solves the following mathematical recurrence function:
 n + 1 if m = 0 A(m, n) = A(m − 1, 1) if m > 0 and n = 0  A(m−1,A(m,n−1) ifm>0andn>0
NOTE: This recurrence relation grows extremelly rapidly, so test it using small m and n values (≤ 4).

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Doesnt print results; here is my code:

Code :

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System.out.print("\nProblem 6 (Enter a positive number): ");
		m = nm.nextInt();
		n = nm.nextInt();
		result3 = Recurfour(m, n);
		System.out.println("Problem 6: " + result3);

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AND the method is

Code :

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public static int Recurfour(int m, int n) {
		int result=0;
 
		if(m == 0) {
			result = n+1; // Base case
		}
		else if(m > 0 && n == 0) {
			result = Recurfour(m-1,1); // Base case
		}
		else if(m > 0 && n > 0){
			result = Recurfour(m-1,Recurfour(m,n-1));
		}
		return result;
	}

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One thing at a time...

Quote:

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I dont understand what you mean

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I mean check your math. Adding some System.out.println statements to print out the values of variables - calculate what you'd expect, then see what it gives - is an invaluable method in debugging code such as this. Once again check your math...say you first call Recursion with 50, your next call will be with 4. Hmmmm.