Find all permutations of a number

[matzahboy]

I have a an integer, n, that is equal to 1379. I want to create an array of all the permutations of n (1397, 1739, 1793, 1937, 1973, 3179, etc...). How would I code this?

Note: I know how many permutations exist. Call that variable "tPerms"

[Fubarable]

At your current level, I'd bet you'd be able to solve this without our help. Why not first give it a go? Also, myself, I'd use characters or String representations of the numbers since we're not really treating these things as numbers.

[Eranga]

I have a an integer, n, that is equal to 1379. I want to create an array of all the permutations of n (1397, 1739, 1793, 1937, 1973, 3179, etc...). How would I code this?

Note: I know how many permutations exist. Call that variable "tPerms"

What you have tried so far, can you show us here?

[matzahboy]

I found the following code (courtesy of Permutations.java). For the particular problem I'm trying to do, I need to find the 1000000th permutation. How would I modify this code to do that?

// print N! permutation of the characters of the string s (in order)
    public  static void perm1(String s) { perm1("", s); }
    private static void perm1(String prefix, String s) {
        int N = s.length();
        if (N == 0) System.out.println(prefix);
        else {
            for (int i = 0; i < N; i++)
               perm1(prefix + s.charAt(i), s.substring(0, i) + s.substring(i+1, N));
        }

    }

[CJSLMAN]

• Do you know what that piece of code does?
• Do you know what the "prefix" and "s" variables are? What they represent?

CJSL

[emceenugget]

I don't understand what the 1 millionth (or nth) permutation means. There is no order to permutations.

[matzahboy]

I'm basically trying to solve problem 24 of project euler (Problem 24 - Project Euler)