#467 - Unique Substrings in Wraparound String

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Problem Description

We define the string base to be the infinite wraparound string of "abcdefghijklmnopqrstuvwxyz", so base will look like this:

"...zabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcd....".

Given a string s, return the number of unique non-empty substrings of s are present in base.

Solution

/**
 * @param {string} s
 * @return {number}
 */
var findSubstringInWraproundString = function(s) {
  const maxLength = new Array(26).fill(0);
  let count = 0;

  for (let i = 0; i < s.length; i++) {
    count = i > 0 && (s.charCodeAt(i) - s.charCodeAt(i - 1) - 1) % 26 === 0 ? count + 1 : 1;
    const index = s.charCodeAt(i) - 97;
    maxLength[index] = Math.max(maxLength[index], count);
  }

  return maxLength.reduce((sum, n) => sum + n, 0);
};