Algorithm Diff Two Arrays - thelastmile/FreeCodeCamp GitHub Wiki

Algorithm Diff Two Arrays

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🏁 Problem Explanation:

Check two arrays and return a new array that contains only the items that are not in either of the original arrays.

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💬 Hint: 1

Merge the list to make it easy to compare functions.

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💬 Hint: 2

Use filter to get the new array, you will need to create a callback function.

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💬 Hint: 3

The best way to go about the callback function is to check if the number from the new merged array is not in both original arrays and return it.

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Spoiler Alert!

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Solution ahead!

🔰 Basic Code Solution (Imperative Solution):

function diffArray(arr1, arr2) {
  var newArr = [];
  // Looping through arr1 to find elements that do not exist in arr2  
  for (var i = 0; i < arr1.length; i++) {
    if (arr2.indexOf(arr1[i]) === -1){
      // Pushing the unique to arr1 elements to the newArr
      newArr.push(arr1[i]);
    }
  }
  // Looping through arr2 to find elements that do not exist in arr1
  for (var j = 0; j < arr2.length; j++) {
    if (arr1.indexOf(arr2[j]) === -1){
      // Pushing the unique to arr2 elements to the newArr    
      newArr.push(arr2[j]);
    }
  }

  return newArr;
}

diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);

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Code Explanation:

Read the comments in the code.

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🌻 Intermediate Code Solution (Declarative Solution):

function diffArray(arr1, arr2) {
  return arr1
    .concat(arr2)
    .filter(
        item => !arr1.includes(item) || !arr2.includes(item)
    )
}

diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);

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Code Explanation:

Explain solution here and add any relevant links

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🚨 Advanced Code Solution (Declarative Solution):

function diffArray(arr1, arr2) {
    return arr1
      .filter(el => !arr2.includes(el))
      .concat(
        arr2.filter(el => !arr1.includes(el))
      )
}

diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);

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Code Explanation:

Explain solution here and add any relevant links

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🏆 Credits:

If you found this page useful, you may say thanks to the contributors by copying and pasting the following line in the main chat:

Thanks @Rafase282 @aganita @abhisekp for your help with Challenge: Diff Two Arrays

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