JS function to compare two arrays of numbers that include duplicates-CodePudding

I'm building a mastermind game. In this game the player needs to guess a secret random number. To make this work I need to have a function that can compare the two arrays and check if there is a match in number and position and/or a match only in the number but not the position.

The problem: This function works well for the most part when there are not repeated numbers in the arrays, but gives me a wrong output when there are repeated numbers.

example:

Random -- arr1 = ['5', '5', '3', '4']
Guess -- arr 2 = ['5', '1', '0', '0,]

expected result

{match: true, exactMatches: 1, matchesByValue: 0}

I'm getting this wrong result:

{match: true, exactMatches: 1, matchesByValue: 1}

Important: matchesByValue means correct number in wrong position. It shouldn't consider numbers that have been already counted as exactMatches.

function compareGuessVsRandom(arr1, arr2) {

    // convert the arrays to sets

    const set1 = new Set(arr1);
    const set2 = new Set(arr2);
    let exactMatches = 0;
    let matchesByValue = 0;
    // check if each value in the first array has the same value and position in the second array
    for (let i = 0; i < arr1.length; i  ) {
      if (arr1[i] == arr2[i]) {
        exactMatches  ;
      } else if (set1.has(arr2[i])) {
        matchesByValue  ;
      }
    }

    // if all checks pass, the arrays are a match
    const result = {
      match: true,
      exactMatches: exactMatches,
      matchesByValue: matchesByValue,
    };
    console.log(result);
    return result;
  }

CodePudding user response：

How do your input arrays look like in your code ? It works when declaring the arrays as blow

let arr1 = [5, 5, 3, 4];
let arr2 = [5, 1, 0, 0];
let result = compareGuessVsRandom(arr1, arr2)
console.log(result)
function compareGuessVsRandom(arr1, arr2) {
  const set1 = new Set(arr1);
  const set2 = new Set(arr2);
  let exactMatches = 0;
  let matchesByValue = 0;
  // check if each value in the first array has the same value and position in the second array
  for (let i = 0; i < arr1.length; i  ) {
    if (arr1[i] == arr2[i]) {
      exactMatches  ;
    } else if (set1.has(arr2[i])) {
      matchesByValue  ;
    }
  }

  // if all checks pass, the arrays are a match
  const result = {
    match: true,
    exactMatches: exactMatches,
    matchesByValue: matchesByValue,
  };
  return result;
}

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

CodePudding user response：

function compareGuessVsRandom (arr1, arr2) {
    // The list of all the indicies at which there is an exact match
    const exactMatchesList = []

    // The amount of matche by value
    let matchesByValue = 0


    for (let i = 0; i < arr1.length; i  )
        if (arr1[i] === arr2[i])
            exactMatchesList.push(i)


    // Init sets with arrays without the exactly-matched values
    const set1 = new Set(arr1.filter((_, i) => !exactMatchesList.includes(i)))
    const set2 = new Set(arr2.filter((_, i) => !exactMatchesList.includes(i)))

    // If set2 contains an element of set1, increment matchesByValue
    for (const e of set1)
        matchesByValue  = set2.has(e)

    // Get the amount of exact matches
    const exactMatches = exactMatchesList.length

    const result = {
        match: exactMatches !== 0 || matchesByValue !== 0,
        exactMatches,
        matchesByValue
    }
    
    return result;
}

const random = [ '5', '5', '3', '4' ]
const guess  = [ '5', '1', '0', '0' ]

console.log(compareGuessVsRandom(random, guess))

CodePudding user response：

The has method returns true if set1 contains the specified element. So regardless of whether an exact match has occurred or not, it will increment 'matchesByValue' even for a match at the index with the exact match.

For example, in a scenario where arr2 has [5,5,0,0]. The first '5'. will increment 'exactMatches' but the second one will also increment 'matchesByValue' by matching it with index 0 of set1.

You can eliminate duplicate matches by comparing indexes of the two types of matches.