<pre class="shiki github-dark shaku"><code>function count(str) { let map = {} for (const char of str) { map[char] = map[char] ? map[char] + 1 : 1 } let max = Object.values(map).sort((a, b) =&gt; b - a)[0] let output = [] for (const [char, val] of Object.entries(map)) { if (val === max) { output.push(char) } } if (output.length === 1) { return output[0] } else { return output }}</code></pre>

O(n)

Given a non-empty string, return the most frequently ocurring character. If there are multiple characters with same occurrance, return an array of the…