How to calculate all possible combinations for a specific range of numbers-CodePudding

I am very new to combinatorics. So that is why I am trying to figure out a way to generate all possible combinations for a specific range of numbers. The problem is that I really do not know how it works. I am trying to understand the logic for 2 days now. Every combination should have three numbers, stored in an extra array, for example: [7,4,8]. The user should be able to choose a range of numbers. I would really appreciate it if somebody could help me.

I was trying to use several for loops to get certain combinations. But that technique seems to be very very complicated and very very unclean. I am struggling with figuring out which possible combination types there can be. I want to write a function that looks like that:

function generateCombinations(min, max) {
   // LOGIC


   return combinations;
}

generateCombinations(0, 10);

// Example OUTPUT
/*

[
 [0,5,10],
 [10,10,10],
 [7,4,1],
. . .
]
*/

Hopefully you can help me. Thank you

CodePudding user response：

It is very straightforward. Just use 3 nested loops(since your combination is of size 3) that iterate from min to max, keep collecting the combinations in an array and you are done.

function generateCombinations(min, max){
let result = [];
 for(let i = min; i <= max;   i){
   for(let j = min; j <= max;   j){
      for(let k = min; k <= max;   k){
        result.push([i, j, k]);
      }
    }
 }
 
 return result;
}

console.log(generateCombinations(0, 10));

CodePudding user response：

Are you looking for combinations between the Arrays so

[7,8,4]
[1,6,0]
[7,1] [7,6] [7,0] [7,1,6] [7,1,0] [7,6,0] [8,1] [8,6] [8,0]

etc.

or should the numbers combine with each other inside the array, so

[7,8,4]
[1,6,0]
[7,8] [7,4] [7,1] [7,6] [7,0] [7,8,1]

etc.