#2645 - Minimum Additions to Make Valid String

Medium • View on LeetCode • View on GitHub

Problem Description

Given a string word to which you can insert letters "a", "b" or "c" anywhere and any number of times, return the minimum number of letters that must be inserted so that word becomes valid.

A string is called valid if it can be formed by concatenating the string "abc" several times.

Solution

/**
 * @param {string} word
 * @return {number}
 */
var addMinimum = function(word) {
  let result = 0;
  let index = 0;

  while (index < word.length) {
    if (word[index] === 'a') {
      if (word[index + 1] === 'b' && word[index + 2] === 'c') {
        index += 3;
      } else if (word[index + 1] === 'b') {
        result += 1;
        index += 2;
      } else if (word[index + 1] === 'c') {
        result += 1;
        index += 2;
      } else {
        result += 2;
        index += 1;
      }
    } else if (word[index] === 'b') {
      if (word[index + 1] === 'c') {
        result += 1;
        index += 2;
      } else {
        result += 2;
        index += 1;
      }
    } else {
      result += 2;
      index += 1;
    }
  }

  return result;
};