Notes on Day 3 of 2023 AdventJS Challenge

• notes • series • javascript • adventjs2023 • typescript

Day 3 continues the test of string and array manipulation problem-solving skills.

Table of Contents

Challenge

The third day involves finding discrepancies between two strings and in this case this first occurrence:

You have the original sequence of original manufacturing steps and the modified modified sequence that may include an extra step or be missing a step.

Your task is to write a function that identifies and returns the first extra step that was added or removed in the manufacturing chain. If there is no difference between the sequences, return an empty string.

Solution

My initial pseudocode basically simply returns the first character from the base string that does not match the other:

  1. Split both strings into characters
    • use longer array as base; otherwise keep original
  2. Iterate over the base array’s characters
  3. Take note of characters that do not match criteria
  4. Return first character matched; otherwise empty string

Here’s my implementation of said pseudocode with filter:

function findNaughtyStep(original, modified) {
  const originalArr = original.split("");
  const modifiedArr = modified.split("");

  return originalArr.length > modifiedArr.length
    ? originalArr.filter((char, index) => modifiedArr[index] !== char)[0]
    : modifiedArr.filter((char, index) => originalArr[index] !== char)[0] || "";
}

Lessons Learned

I had several versions of the implementation because some of the secret tests failed:

  • the function keeps returning all characters that did not match
  • the function just returns the difference from the modified string (hence my decided in # 1 to check which one’s longer)

I know there’s more efficient ways and better array prototypes to use and I will keep updating this page after my experiments from this first try to look back at what I have accomplished.

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