<h2><a href="https://leetcode.com/problems/minimum-number-of-changes-to-make-binary-string-beautiful/">2914. Minimum Number of Changes to Make Binary String Beautiful</a></h2><h3>Medium</h3><hr><div><p>You are given a <strong>0-indexed</strong> binary string <code>s</code> having an even length.</p>

<p>A string is <strong>beautiful</strong> if it's possible to partition it into one or more substrings such that:</p>

<ul>

<li>Each substring has an <strong>even length</strong>.</li>

<li>Each substring contains <strong>only</strong> <code>1</code>'s or <strong>only</strong> <code>0</code>'s.</li>

</ul>

<p>You can change any character in <code>s</code> to <code>0</code> or <code>1</code>.</p>

<p>Return <em>the <strong>minimum</strong> number of changes required to make the string </em><code>s</code> <em>beautiful</em>.</p>

<p>&nbsp;</p>

<p><strong class="example">Example 1:</strong></p>

<pre><strong>Input:</strong> s = "1001"

<strong>Output:</strong> 2

<strong>Explanation:</strong> We change s[1] to 1 and s[3] to 0 to get string "1100".

It can be seen that the string "1100" is beautiful because we can partition it into "11|00".

It can be proven that 2 is the minimum number of changes needed to make the string beautiful.

</pre>

<p><strong class="example">Example 2:</strong></p>

<pre><strong>Input:</strong> s = "10"

<strong>Output:</strong> 1

<strong>Explanation:</strong> We change s[1] to 1 to get string "11".

It can be seen that the string "11" is beautiful because we can partition it into "11".

It can be proven that 1 is the minimum number of changes needed to make the string beautiful.

</pre>

<p><strong class="example">Example 3:</strong></p>

<pre><strong>Input:</strong> s = "0000"

<strong>Output:</strong> 0

<strong>Explanation:</strong> We don't need to make any changes as the string "0000" is beautiful already.

</pre>

<p>&nbsp;</p>

<p><strong>Constraints:</strong></p>

<ul>

<li><code>2 &lt;= s.length &lt;= 10⁵</code></li>

<li><code>s</code> has an even length.</li>

<li><code>s[i]</code> is either <code>'0'</code> or <code>'1'</code>.</li>

</ul>

</div>