<p>The <strong>power</strong> of the string is the maximum length of a non-empty substring that contains only one unique character.</p> <p>Given a string <code>s</code>, return <em>the <strong>power</strong> of</em> <code>s</code>.</p> <p> </p> <p><strong>Example 1:</strong></p> <pre> <strong>Input:</strong> s = "leetcode" <strong>Output:</strong> 2 <strong>Explanation:</strong> The substring "ee" is of length 2 with the character 'e' only. </pre> <p><strong>Example 2:</strong></p> <pre> <strong>Input:</strong> s = "abbcccddddeeeeedcba" <strong>Output:</strong> 5 <strong>Explanation:</strong> The substring "eeeee" is of length 5 with the character 'e' only. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= s.length <= 500</code></li> <li><code>s</code> consists of only lowercase English letters.</li> </ul>