Discussion on: A common coding interview question

View post

Replies for: simplified the solution by using Sets and corrected the answer to correspond the assignment const lines = ['1,2,3,4,5,6', '2,4,6,7,8,9,10', '1,2...

couldn't help myself.. improved the performance by sorting sets and checking result set. Changed the api from array input to n-amount of params. Also input is filtered from not a number

function FindIntersection(...lines) {  
  const getSet = (line = '') => {
    const numbers = line.split(',').map(number => parseInt(number))
    return new Set(numbers.filter(number => !isNaN(number)))
  }
  const sets = lines.map(getSet)
  const [shortestSet, ...otherSets] = [...sets].sort((setA, setB) => setA.size - setB.size)
  const defaultSet = lines.length > 1 ? shortestSet : new Set([])
  const resultSet = otherSets.reduce((resultSet, set) => {
    const commonNumbers = [...resultSet].filter(number => set.has(number))
    return new Set(commonNumbers)
  }, defaultSet)
  const result = [...resultSet]
  return result.length > 0 ? result : 'false'
}

console.log(FindIntersection()) // outputs: false
console.log(FindIntersection('1')) // outputs: false
console.log(FindIntersection('2', '3')) // outputs: false
console.log(FindIntersection('-1, 0', '0')) // outputs: [0]
console.log(FindIntersection('a, 3', 'b, c, 3')) // outputs: [3]
console.log(FindIntersection('-2, 3', '-4, -2')) // outputs: [-2]
console.log(FindIntersection('1,2,3,4', '2,3,4,5', '3,4,5,6')) // outputs: [3, 4]
console.log(FindIntersection('1,2,3,4,5,6', '2,4,6,7,8,9,10', '1,2,3,4,5,6,8')) // outputs: [2, 4, 6]
console.log(FindIntersection(...['1, 3, 4, 7, 13', '1, 2, 4, 13, 15'])) // outputs: [1, 4, 13]

Firee80 • Nov 28 '19

Decided to have a one more improvement for performance (when one Set has size = 0, so no need to reduce other Sets. Also result from reduce is directly an array of numbers).
Also my apologies to @elisabethgross as I noticed the tag #codenewbie in the challenge and my answer isn't really for newbies.

function FindIntersection(...lines) {  
  const getSet = (line = '') => {
    const numbers = line.split(',').map(number => parseInt(number))
    return new Set(numbers.filter(number => !isNaN(number)))
  }
  const sets = lines.map(getSet)
  const [shortestSet, ...otherSets] = [...sets].sort((setA, setB) => setA.size - setB.size)
  const setsToReduce = shortestSet && shortestSet.size > 0 ? otherSets : [] 
  const defaultCommonNumbers = lines.length > 1 ? [...shortestSet] : []
  const resultCommonNumbers = setsToReduce.reduce((commonNumbers, set) => 
    commonNumbers.filter(number => set.has(number)), defaultCommonNumbers)
  return resultCommonNumbers.length > 0 ? resultCommonNumbers : 'false'
}

console.log(FindIntersection()) // outputs: false
console.log(FindIntersection('1')) // outputs: false
console.log(FindIntersection('2', '3')) // outputs: false
console.log(FindIntersection('-1, 0', '0')) // outputs: [0]
console.log(FindIntersection('a, 3', 'b, c, 3')) // outputs: [3]
console.log(FindIntersection('-2, 3', '-4, -2')) // outputs: [-2]
console.log(FindIntersection('1,2,3,4', '2,3,4,5', '3,4,5,6')) // outputs: [3, 4]
console.log(FindIntersection('1,2,3,4,5,6', '2,4,6,7,8,9,10', '1,2,3,4,5,6,8')) // outputs: [2, 4, 6]
console.log(FindIntersection(...['1, 3, 4, 7, 13', '1, 2, 4, 13, 15'])) // outputs: [1, 4, 13]