Achieving a Subset Using Functional Programming

Question

Achieving a Subset Using Functional Programming

Looking for suggestions on implementing a function that takes an array A containing n elements and a number k as input. The function should return an array consisting of all subsets of size k from A, with each subset represented as an array.

Please define the type of the function and provide a minimum of 3 tests using assert to ensure functionality. The function should be written in a functional programming style using Javascript/Typescript.

For example: FunSubsets ([1,2,3],2) => [[1,2],[1,3],[2,3]]

Open to any ideas!

javascript typescript

Answer 1

Answer №1

One potential solution is to implement a generator function that includes an additional parameter for storing the temporary result set.

function* subsets(values, size, parts = []) {
    var i;

    size--;
    for (i = 0; i < values.length; i++) {
        if (size) {
            yield* subsets(values.slice(i + 1), size, [...parts, values[i]]);
        } else {
            yield [...parts, values[i]];
        }
    }
}

console.log([...subsets([1, 2, 3], 2)]);
console.log([...subsets([1, 2, 3, 4, 5], 2)]);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

One potential solution is to implement a generator function that includes an additional parameter for storing the temporary result set.

function* subsets(values, size, parts = []) {
    var i;

    size--;
    for (i = 0; i < values.length; i++) {
        if (size) {
            yield* subsets(values.slice(i + 1), size, [...parts, values[i]]);
        } else {
            yield [...parts, values[i]];
        }
    }
}

console.log([...subsets([1, 2, 3], 2)]);
console.log([...subsets([1, 2, 3, 4, 5], 2)]);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

Answer №2

Iterate through the array and for each element, iterate again to create a slice with the length k - 1. Concatenate it with the current element of the first loop and add it to a temporary array that is returned in the end.

let myArray = [1, 2, 3, 4];

let kValue = 2;

function findSubSets(arr, k) {

  let tempArray = [];
  for (var i = 0; i < arr.length; i++) {
    for (let j = i + 1; j < arr.length; j++) {
      let slice = arr.slice(j, j + k - 1);
      slice.push(arr[i]);
      tempArray.push(slice.reverse());
    }
  }
  return tempArray;
}

let foundSubSets = findSubSets(myArray, kValue);

console.log(JSON.stringify(foundSubSets));

Answer 4

Iterate through the array and for each element, iterate again to create a slice with the length k - 1. Concatenate it with the current element of the first loop and add it to a temporary array that is returned in the end.

let myArray = [1, 2, 3, 4];

let kValue = 2;

function findSubSets(arr, k) {

  let tempArray = [];
  for (var i = 0; i < arr.length; i++) {
    for (let j = i + 1; j < arr.length; j++) {
      let slice = arr.slice(j, j + k - 1);
      slice.push(arr[i]);
      tempArray.push(slice.reverse());
    }
  }
  return tempArray;
}

let foundSubSets = findSubSets(myArray, kValue);

console.log(JSON.stringify(foundSubSets));

Achieving a Subset Using Functional Programming

Answer №1

Answer №2

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