#1624 - Largest Substring Between Two Equal Characters

Easy • View on LeetCode • View on GitHub

Problem Description

Given a string s, return the length of the longest substring between two equal characters, excluding the two characters. If there is no such substring return -1.

A substring is a contiguous sequence of characters within a string.

Solution

/**
 * @param {string} s
 * @return {number}
 */
var maxLengthBetweenEqualCharacters = function(s) {
  const charFirstIndex = new Map();
  let maxLength = -1;

  for (let i = 0; i < s.length; i++) {
    const char = s[i];
    if (charFirstIndex.has(char)) {
      maxLength = Math.max(maxLength, i - charFirstIndex.get(char) - 1);
    } else {
      charFirstIndex.set(char, i);
    }
  }

  return maxLength;
};