3169:Add solution for counting free days without meetings

Author: Amir-16

Medium/3169. Count Days Without Meetings/solution.php

@@ -0,0 +1,41 @@
+<?php
+class Solution
+{
+    /**
+     * @param Integer $days
+     * @param Integer[][] $meetings
+     * @return Integer
+     */
+    public function countDays($days, $meetings)
+    {
+        sort($meetings);
+
+        $freeDays = 0;
+
+        $lastEnd = 0;
+
+        foreach ($meetings as $meeting) {
+            list($start, $end) = $meeting;
+
+            if ($start > $lastEnd + 1) {
+                $freeDays += $start - $lastEnd - 1;
+            }
+
+            $lastEnd = max($lastEnd, $end);
+        }
+
+        $freeDays += $days - $lastEnd;
+
+        return $freeDays;
+    }
+}
+
+$solution = new Solution();
+
+$days = 7;
+
+$meetings = [[1, 2], [2, 3], [3, 4]];
+
+$result = $solution->countDays($days, $meetings);
+
+echo $result;