weight-for-weight.md

Weight for weight ^{5 Kyu}

^{LINK TO THE KATA - ALGORITHMS}

Description

My friend John and I are members of the "Fat to Fit Club (FFC)". John is worried because each month a list with the weights of members is published and each month he is the last on the list which means he is the heaviest.

I am the one who establishes the list so I told him: "Don't worry any more, I will modify the order of the list". It was decided to attribute a "weight" to numbers. The weight of a number will be from now on the sum of its digits.

For example 99 will have "weight" 18, 100 will have "weight" 1 so in the list 100 will come before 99.

Given a string with the weights of FFC members in normal order can you give this string ordered by "weights" of these numbers?

Example:

"56 65 74 100 99 68 86 180 90" ordered by numbers weights becomes:

"100 180 90 56 65 74 68 86 99"

When two numbers have the same "weight", let us class them as if they were strings (alphabetical ordering) and not numbers:

180 is before 90 since, having the same "weight" (9), it comes before as a string.

All numbers in the list are positive numbers and the list can be empty.

Notes

• it may happen that the input string have leading, trailing whitespaces and more than a unique whitespace between two consecutive numbers
• For C: The result is freed.

Solution

const sumOfDigits = strNum => {
  return strNum.split('').reduce((acc, cur) => acc + Number(cur), 0)
}

const orderWeight = str => {
  const numbers = str.split(' ')

  const pairs = []
  numbers.forEach(strNum => {
    pairs.push({ sum: sumOfDigits(strNum), stringNumber: strNum })
  })

  const orderedPairs = pairs.sort((a, b) => {
    return a.sum === b.sum
      ? a.stringNumber.localeCompare(b.stringNumber)
      : a.sum - b.sum
  })

  const result = []
  orderedPairs.forEach(item => {
    result.push(item.stringNumber)
  })

  return result.join(' ')
}