The Problem

Write a function that, given the start startNum and end endNum values, return an array containing all the numbers inclusive to that range.

Your task here is to return all the numbers between two numbers, including the two numbers given.

We add the first number to an array hold, then increment the number, push it to hold until we get all the numbers within the desired range. Look out for edge cases~

This problem comes from Edabit, composed by Deep Xavier.

My solution

//i: number
//i: number
//o: array

//declare inclusiveArray, has two parameters
//declare empty array hold
function inclusiveArray(a, b, hold = []){
if (typeof a !== 'number' || typeof b !== 'number') return 'invalid argument';
// base case if startNum === endNum+1 return hold
  if (a === b + 1) return hold;
  if (a > b + 2) return [a];
// recursive case: push startNum to hold,
  hold.push(a);
// add 1 to startNum
  return inclusiveArray(++a, b, hold );
}

console.log(inclusiveArray(2,5)); // [ 2, 3, 4, 5 ]
console.log(inclusiveArray(1,10)); // [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]
console.log(inclusiveArray(20,45)); // [ 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45 ]
console.log(inclusiveArray('sandwich',45)); // 'invalid argument'
console.log(inclusiveArray(17,5)); // [17]

Other solutions:

function inclusiveArray(startNum, endNum) {
  return startNum >= endNum ? [startNum] : [startNum, ...inclusiveArray(startNum + 1, endNum)];
}

const inclusiveArray = (s, e) => s >= e? [s] : [...inclusiveArray(s, e-1), e]


// ChatGPT solution - it doesn't handle the cases where a is greater than b correctly.

function range(startNum, endNum) {
  if (startNum > endNum) {
    return [];
  }
  return [startNum].concat(range(startNum + 1, endNum));
}