A very big sum - Hacker Rank

Question

I am trying to solve "A very big sum" challenge on Hacker Rank: https://www.hackerrank.com/challenges/a-very-big-sum/problem

In there I have to sum all the numbers in the array given so I came up with two solutions:

First solution

function aVeryBigSum(ar){
  let sum = 0;
  for(let i = 0; i < ar.length; i++){
     sum += i;
   }
}

Second Solution

function(ar){
 let sum = ar.reduce((accumulator, currentValue) => {
  accumulator + currentValue;
    });
}

But none of them work and I don´t know why, I am thiniking maybe I am not writing it as Hacker Rank wants me to but I am not sure

Eyeleteer

Might have something to do with the fact that you aren't returning anything in either function – Sorel

Answer 1

sum += i; should be sum += ar[i];

Also return sum

function aVeryBigSum(ar){
  let sum = 0;
  for(let i = 0; i < ar.length; i++){
     sum += ar[i];
  }
  return sum;
}

Also reducer function should be like

function a(ar){
  let sum = (accumulator, currentValue) => accumulator + currentValue;
  return ar.reduce(sum);
}

Monotonous

Answer 2

In your first solution, you should index the array instead of just adding up the indexes:

function aVeryBigSum(ar){
  let sum = 0;
  for(let i = 0; i < ar.length; i++){
     sum += ar[i];
  }
  return sum;
}

To sum the array with reduce:

function aVeryBigSum(ar){
  return ar.reduce((a, b) => a + b, 0);
}

Also, note that you should return values in the functions. Although this works for arrays with small numbers, you should think about what can happen if the sum gets very large. (See the note section on HackerRank.)

Virtuoso

Answer 3

you can also use this one

    function aVeryBigSum(ar) {
    // Write your code here
   let sum = 0;
    ar.map((num) => {
        sum += num
    })
    return sum;
}

Effortless

Answer 4

both of your solutions do not RETURN the sum

function aVeryBigSum(ar) {
    let sum = 0;
    ar.forEach(s =>{
    sum += s;
  });
  return sum;
}

Clance

You should help explain, why the OPs solutions aren't working and why this answer works. – Olivette

Answer 5

You need to handle all edge cases and corner cases on these HackerRank challenges. Observe comments, this passes all.

// ** Input **
const input1 = [1000000001, 1000000002, 1000000003, 1000000004, 1000000005]
const input2 = [5555]
const input3 = '10'

// ** Solution **
function aVeryBigSum(ar) {

  // Declare Working Variable
  let sum = ar

  // If Already Integer >> Return as Sum
  if (typeof sum == 'number') {
    return sum
  }

  // If String or Object
  if (typeof sum == 'string' || typeof sum == 'object') {

    // Split String into Array at Space
    if (typeof sum == 'string') { sum = sum.split(' ') }

    // Reduce
    sum = sum.reduce((a,b) => {

      // If Number > Parse as Integer
      (typeof a == 'number' && typeof b == 'number')
      a = parseInt(a)
      b = parseInt(b)

      return a += b
    }, 0)

    // Return Sum
    return sum
  }
}

// ** Testing **
console.log(aVeryBigSum(input1))
console.log(aVeryBigSum(input2))
console.log(aVeryBigSum(input3))

Entourage

Answer 6

sample input [1000000001 ,1000000002 ,1000000003, 1000000004, 1000000005]

function aVeryBigSum(ar) {
  let score = 0;

  for(let i =0; i< ar.length;i++) {
    score += parseInt(ar[i].toString().substring(0));
  }

  return score;
}

Offenbach

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center. – Rurik

Answer 7

public static long aVeryBigSum(List<Long> ar) {
    return ar.stream().reduce(0L, Long::sum);
}

Visigoth