iterate array of numbers to calculate all possible combinations with given algorithm - javscript

Question

i need to iterate an array of x numbers in given order and calculate all possible combinations, for example:

I have this Array of 5 numbers [01,02,03,04,05], this is the condition to calculate the combinations:

expected output:

01 02 01 03 01 04 01 05 05 04 05 03 05 02 04 03 04 02 03 02

Example of array of 6 numbers [00,00,00,10,40,60], this is the condition to calculate the combinations:

expected output:

00 00 00 00 00 10 00 40 00 60 60 40 60 10 60 00 60 00 00 00 00 10 00 40 40 10 40 00 00 10

so the array can be from length 3 to x length.

this is what i have

function calculate(numbers){
    let combinations = [];
    if(numbers.length == 2){
      combinations = [numbers[0] + ' '+ numbers[1]];
    }else{
      for(let i = 1; i < numbers.length; i++){
        combinations.push(numbers[0] + ' '+ numbers[i]);
      }
      for(let i =  numbers.length - 1; i  >= 1; i--){
        combinations.push(numbers[numbers.length - 1] + ' '+ numbers[i]);
      }
      
    }
    return combinations
  }

let numbers = [01,02,03,04,05];
console.log(calculate(numbers))

thanks in advance

Try to make the example as *small* as possible to make it easier for people to read — MrMythical, Sep 08 '21 at 02:11
An infinite length input is apt to take an unacceptable amount of time to produce a result. :-) — danh, Sep 08 '21 at 02:11
Does this answer your question? [Javascript - Generating all combinations of elements in a single array (in pairs)](https://stackoverflow.com/questions/43241174/javascript-generating-all-combinations-of-elements-in-a-single-array-in-pairs) — kmoser, Sep 08 '21 at 04:31

score 0 · Answer 1 · answered Sep 08 '21 at 02:21

I recreated the first example you gave in a more efficient manner, this also greatly simplifies the code:

Now for the code

const data = ["01", "02", "03", "04", "05"];

const possibilities = [];

for (let i = 0; i < data.length; i++) {
  let j = i + 1;

  while (j < data.length) {
    possibilities.push(data[i] + " " + data[j]);
    j++;
  }
}

console.log(possibilities);

score 0 · Answer 2 · answered Sep 08 '21 at 02:22

0

nums.slice(0, nums.length-1).map(
  (n, i) => nums.slice(i+1).map(
    sn => `${n} ${sn}`
  ).join(' ')
).join(' ')

Hope it is what you want.

answered Sep 08 '21 at 02:22

Silo QIAN

60
8

score 0 · Answer 3 · answered Sep 08 '21 at 03:46

The way you connect the numbers made you think over complicated. If you connect them in this way, then the logic to get all possible combinations is simple. i.e. for each number, pair with every numbers after it. That's all.

const numbers = [1,2,3,4,5];
let combinations = [];
for(let i = 0 ; i < numbers.length; i++)
{
  for(let j = i+1; j < numbers.length; j++)
  {
    combinations.push([numbers[i],numbers[j]]);
  }
}
console.log(combinations);

iterate array of numbers to calculate all possible combinations with given algorithm - javscript

3 Answers3