Adding medium/hard puzzles & challenges...

puzzles/medium/telephone-numbers.php

@@ -0,0 +1,29 @@
+<?php
+// https://www.codingame.com/ide/puzzle/telephone-numbers
+// Xavier Morel - 2016-03-17
+
+$maintab = array();
+$lines   = (int) fgets(STDIN);
+$result  = 0;
+
+$i = 0;
+while ($i < $lines) {
+    $nbr = fgets(STDIN);
+    $nbr = trim($nbr);
+
+    $c = strlen($nbr);
+    $tab = &$maintab;
+    for ($j = 0; $j < $c; $j++) {
+        $number = $nbr[$j];
+        if (!isset($tab[$number])) {
+            $tab[$number] = array();
+            $result++;
+            $tab =& $tab[$number];
+        } else {
+            $tab =& $tab[$number];
+        }
+    }
+    $i++;
+}
+
+echo $result;