maxDiff.js

/**
You are given a string s consisting of lowercase English letters.

Your task is to find the maximum difference diff = freq(a1) - freq(a2) between the frequency of characters a1 and a2 in the string such that:

a1 has an odd frequency in the string.
a2 has an even frequency in the string.
Return this maximum difference.

Example 1:
Input: s = "aaaaabbc"
Output: 3

Explanation:
The character 'a' has an odd frequency of 5, and 'b' has an even frequency of 2.
The maximum difference is 5 - 2 = 3.

Example 2:
Input: s = "abcabcab"
Output: 1

Explanation:
The character 'a' has an odd frequency of 3, and 'c' has an even frequency of 2.
The maximum difference is 3 - 2 = 1.
 
Constraints:
3 <= s.length <= 100
s consists only of lowercase English letters.
s contains at least one character with an odd frequency and one with an even frequency.

* @param {string} s
* @return {number}
*/
var maxDifference = function (s) {
  let maxOdd = 0;
  let minEven = 0;

  let freqMap = new Map()

  for (const char of s) {
    freqMap.set(char, (freqMap.get(char) || 0) + 1);
  }

  let freqValues = [...freqMap.values()]

  for (const freq of freqValues) {
    if (freq % 2 === 1) {
      maxOdd = Math.max(maxOdd, freq);
    } else {
      if (minEven === 0 || freq < minEven) {
        minEven = freq;
      }
    }
  }
  return maxOdd - minEven;
};