Question 304036 in Javascript Question posted in
A very good W3school tutorial can be found here.

factor an integer as the sum of 20 different random integers greater than zero with Javascript

I have a small problem that I can’t solve.

I would like, with a JavaScript code, to decompose an integer, such as the sum of several integers greater than zero and different from each other.

For now, I have managed to create the code below.
The problem is that it generates integers greater than zero, which however can be equal to each other.

How can I make them different from each other?

JavaScript code

const targetNumber = 40; 
const numTerms = 20; 

const result = BreakDownNumber(targetNumber, numTerms);
console.log("number to break down:", targetNumber);
console.log("random numbers:", result);

 
 function BreakDownNumber(targetNumber, numTerms) {

     let numbers = [];

     function getRandomNumber(min, max) {
       return Math.floor(Math.random() * (max - min + 1)) + min;
     }
  
     let sum = 0;
     for (let i = 0; i < numTerms - 1; i++) {
       let randomNumber = getRandomNumber(1, targetNumber - sum - (numTerms - i - 1));
       numbers.push(randomNumber);
       sum += randomNumber;
    }
  
     // Last number
     numbers.push(targetNumber - sum);
  
     return numbers;
   }

I probably have to change everything, but I don’t know.
I know it’s a trivial question but I’m truly a beginner. 😉

I gladly accept any advice and help.

Thanks a lot to everyone.

Happy programming!

Tags:

2

Answers


  1. 0

    You can use a while loop to generate a random number, and if it does not conform to the rules do not increment i

    Note:

    the last number cannot mathematically conform to your rules if you have random numbers, it’s just up to chance + the last number goes 1 over the numTerms (I left it like that in case it was intentional)

    (I changed the numbers to make it run quicker)

    const targetNumber = 10; 
const numTerms = 2; 

const result = BreakDownNumber(targetNumber, numTerms);
console.log("number to break down:", targetNumber);
console.log("random numbers:", result);

 
 function BreakDownNumber(targetNumber, numTerms) {

     let numbers = [];

     function getRandomNumber(min, max) {
       return Math.floor(Math.random() * (max - min + 1)) + min;
     }
  
     let sum = 0;
     let i = 0
     while (i < numTerms) {
       let randomNumber = getRandomNumber(1, targetNumber - sum);
       if (!(numbers.includes(randomNumber))) {
            numbers.push(randomNumber);
            sum += randomNumber;
            i++
        }
    }
  
     // Last number
     numbers.push(targetNumber - sum);
  
     return numbers;
   }
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  2. 0

    The smallest sum of n different positive integers is 1+2+…+n = n(n+1)/2. So for a given n, if the target is smaller than that, there is no solution.

    Otherwise, one valid solution is 1, 2, …, n-1, (target – n).

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