/*SAMPLE INPUTS AND OUTPUTS*/
let input = ['w','h','a','t',' ','o','n',' ','e','a','r','t','h',' ','a','r','e',' ','y','o','u',' ','t','a','l','k','i','n','g',' ','a','b','o','u','t','?'];
let output = ['w','h','a','a','t',' ','o','o','n',' ','e','e','a','a','r','t','h',' ','a','a','r','e','e',' ','y','o','o','u','u',' ','t','a','a','l','k','i','i','n','g',' ','a','a','b','o','o','u','u','t','?'];

//I: array of chars
//O: array of chars with each vowel doubles
//C: don't convert to strings, don't create other data structures, O(N) (currently violating O(N))
//E: none

//Assumptions:
  // y is not a vowel
  // input will be in lower case

let doubleVowels = (array) => {
  let count = array.length;
  for (let i = 0; i < array.length; i++) { // O(N)
    if (array[i] === 'a' ||
        array[i] === 'e' ||
        array[i] === 'i' ||
        array[i] === 'o' ||
        array[i] === 'u'
    ) {
      count += 1;
    }
  }
  for (let i = count; i > 0; i--) { // O(N)
    console.log('loc: ', i, ' char: ', array[i]);
    if (array[i] === 'a' ||
        array[i] === 'e' ||
        array[i] === 'i' ||
        array[i] === 'o' ||
        array[i] === 'u'
    ) {
      let doubledChar = array[i];
      // how do i shift characters up without increasing TC?
      // THIS is not the right way...
      array.splice(i, 0, doubledChar); // O(N)
    }
  }
  return array;
};

/*TESTING*/
console.log(JSON.stringify(doubleVowels(input)) === JSON.stringify(output));