AI solution for JavaScript Coding Question on BFE.dev
145. most frequently occurring character

One possible solution in JavaScript:

function count(str) {
  const countMap = {};
  let maxCount = 0;
  for (let i = 0; i < str.length; i++) {
    const char = str[i];
    countMap[char] = (countMap[char] || 0) + 1;
    maxCount = Math.max(maxCount, countMap[char]);
  }
  const result = [];
  for (const char in countMap) {
    if (countMap[char] === maxCount) {
      result.push(char);
    }
  }
  return result.length === 1 ? result[0] : result;
}

Explanation:

• We use an object countMap to map each character to its count in the string.
• We also keep track of the maxCount of any character seen so far.
• We loop through the string and update the count of each character in countMap.
• We update maxCount if necessary.
• Finally, we loop through countMap again and add any character that has count equal to maxCount to an array result.
• If result has only one element, we return that element, otherwise we return result itself.

The time complexity of this approach is O(n), where n is the length of the string, because we need to loop through the string once to update countMap and maxCount, and then loop through countMap once again to find the characters with the max count.

The space complexity is O(k), where k is the number of distinct characters in the string, because we need to store each distinct character as a key in countMap. In the worst case, where all characters are distinct, the space complexity is O(n).