Shifting Letters II
<p>You are given a string <code>s</code> of lowercase English letters and a 2D integer array <code>shifts</code> where <code>shifts[i] = [start<sub>i</sub>, end<sub>i</sub>, direction<sub>i</sub>]</code>. For every <code>i</code>, <strong>shift</strong> the characters in <code>s</code> from the index <code>start<sub>i</sub></code> to the index <code>end<sub>i</sub></code> (<strong>inclusive</strong>) forward if <code>direction<sub>i</sub> = 1</code>, or shift the characters backward if <code>direction<sub>i</sub> = 0</code>.</p>

<p>Shifting a character <strong>forward</strong> means replacing it with the <strong>next</strong> letter in the alphabet (wrapping around so that <code>&#39;z&#39;</code> becomes <code>&#39;a&#39;</code>). Similarly, shifting a character <strong>backward</strong> means replacing it with the <strong>previous</strong> letter in the alphabet (wrapping around so that <code>&#39;a&#39;</code> becomes <code>&#39;z&#39;</code>).</p>

<p>Return <em>the final string after all such shifts to </em><code>s</code><em> are applied</em>.</p>

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

<pre>
<strong>Input:</strong> s = &quot;abc&quot;, shifts = [[0,1,0],[1,2,1],[0,2,1]]
<strong>Output:</strong> &quot;ace&quot;
<strong>Explanation:</strong> Firstly, shift the characters from index 0 to index 1 backward. Now s = &quot;zac&quot;.
Secondly, shift the characters from index 1 to index 2 forward. Now s = &quot;zbd&quot;.
Finally, shift the characters from index 0 to index 2 forward. Now s = &quot;ace&quot;.</pre>

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

<pre>
<strong>Input:</strong> s = &quot;dztz&quot;, shifts = [[0,0,0],[1,1,1]]
<strong>Output:</strong> &quot;catz&quot;
<strong>Explanation:</strong> Firstly, shift the characters from index 0 to index 0 backward. Now s = &quot;cztz&quot;.
Finally, shift the characters from index 1 to index 1 forward. Now s = &quot;catz&quot;.
</pre>

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

<ul>
	<li><code>1 &lt;= s.length, shifts.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>shifts[i].length == 3</code></li>
	<li><code>0 &lt;= start<sub>i</sub> &lt;= end<sub>i</sub> &lt; s.length</code></li>
	<li><code>0 &lt;= direction<sub>i</sub> &lt;= 1</code></li>
	<li><code>s</code> consists of lowercase English letters.</li>
</ul>
Array; String; Prefix Sum
func shiftingLetters(s string, shifts [][]int) string {
	n := len(s)
	d := make([]int, n+1)
	for _, e := range shifts {
		if e[2] == 0 {
			e[2]--
		}
		d[e[0]] += e[2]
		d[e[1]+1] -= e[2]
	}
	for i := 1; i <= n; i++ {
		d[i] += d[i-1]
	}
	ans := []byte{}
	for i, c := range s {
		j := (int(c-'a') + d[i]%26 + 26) % 26
		ans = append(ans, byte('a'+j))
	}
	return string(ans)
}