Find the Difference
<p>You are given two strings <code>s</code> and <code>t</code>.</p>

<p>String <code>t</code> is generated by random shuffling string <code>s</code> and then add one more letter at a random position.</p>

<p>Return the letter that was added to <code>t</code>.</p>

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

<pre>
<strong>Input:</strong> s = &quot;abcd&quot;, t = &quot;abcde&quot;
<strong>Output:</strong> &quot;e&quot;
<strong>Explanation:</strong> &#39;e&#39; is the letter that was added.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;&quot;, t = &quot;y&quot;
<strong>Output:</strong> &quot;y&quot;
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>0 &lt;= s.length &lt;= 1000</code></li>
	<li><code>t.length == s.length + 1</code></li>
	<li><code>s</code> and <code>t</code> consist of lowercase English letters.</li>
</ul>
Bit Manipulation; Hash Table; String; Sorting
impl Solution {
    pub fn find_the_difference(s: String, t: String) -> char {
        let s = s.as_bytes();
        let t = t.as_bytes();
        let n = s.len();
        let mut count = [0; 26];
        for i in 0..n {
            count[(s[i] - b'a') as usize] += 1;
            count[(t[i] - b'a') as usize] -= 1;
        }
        count[(t[n] - b'a') as usize] -= 1;
        char::from(b'a' + (count.iter().position(|&v| v != 0).unwrap() as u8))
    }
}
