<p>In a string <code><fontface="monospace">s</font></code> of lowercase letters, these letters form consecutive groups of the same character.</p>
<p>For example, a string like <code>s = "abbxxxxzyy"</code> has the groups <code>"a"</code>, <code>"bb"</code>, <code>"xxxx"</code>, <code>"z"</code>, and <code>"yy"</code>.</p>
<p>A group is identified by an interval <code>[start, end]</code>, where <code>start</code> and <code>end</code> denote the start and end indices (inclusive) of the group. In the above example, <code>"xxxx"</code> has the interval <code>[3,6]</code>.</p>
<p>A group is considered <strong>large</strong> if it has 3 or more characters.</p>
<p>Return <em>the intervals of every <strong>large</strong> group sorted in <strong>increasing order by start index</strong></em>.</p>
