Permutations Program

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Background
Permutations are the number of possible orders for a given group of elements. You can determine the permutation by multiplying by the number of possible choices for each selection.

For example, let's say you are given 4 distinct elements, and want to know how many ways you can arrange 3 of them. You can pick from 4 elements for the first choice, 3 for the second, and 2 for the third:

4 Permute 3 = 4 * 3 * 2 = 24 possible ways

(See below for additional examples.)

Challenge Formula
The general Permutation formula for a permute b is:
a * (a-1) * (a-2)... (until you've multiplied b elements.)

Can you calculate a permute b?

Challenge

Given two numbers a and b, calculate and return a Permute b as above.

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Comments

許友誠

May 15, 5:06 AM

import java.util.Scanner;

public class Main {

static int doStuff(int a, int b)
{
        int count=b;
        int  ans=1;

     for(int i=0;i<b;i++)

cont...

     {

        ans=ans*(a-i);
     }

    return ans;
    //your code here
}


//boilerplate code
public static void main(String[] args)
{
    Scanner in = new Scanner(System.in);

    int n = in.nextInt();
    for(int i=0; i<n; i++){
        int a = in.nextInt();
        int b= in.nextInt();
        System.out.println(doStuff(a, b));
    }
}

}

thales
Jul 16, 12:19 PM

my code
Bolke
Sep 25, 6:24 AM

That was tricky. Took me! my code

Permutations Program

Challenge

Comments

許友誠

thales

Bolke