Alphabet-symmetry.js

/*
  Consider the word "abode". We can see that the letter a is in position 1 and b is in position 2. In the alphabet, a and b are also in positions 1 and 2. Notice also that d and e in abode occupy the positions they would occupy in the alphabet, which are positions 4 and 5.

  Given an array of words, return an array of the number of letters that occupy their positions in the alphabet for each word. For example,

  solve(["abode","ABc","xyzD"]) = [4, 3, 1]
  See test cases for more examples.

  Input will consist of alphabet characters, both uppercase and lowercase. No spaces.

  Good luck!
*/

// Answer:

function solve(arr) {
  return arr.map((str) => {
    str = str.toLowerCase();
    let result = 0;
    for (let i = 0; i < str.length; i++) {
      if (i + 1 === str[i].charCodeAt() - 96) result++;
    }
    return result;
  });
}

// BigO: O(n + k) where k is the max length of string and n is the length of array.