Data commit

Task/Kaprekar-numbers/PHP/kaprekar-numbers.php

@@ -0,0 +1,18 @@
+set_time_limit(300);
+
+print_r(array_filter(range(1, 10000), 'isKaprekar'));
+echo count(array_filter(range(1, 1000000), 'isKaprekar'));
+
+function isKaprekar($n) {
+    $a = $n * $n;
+    $b = bcmod("$a", "10");
+    for ($d = 1, $t = 0; $a > 0; $d *= 10) {
+        $b += $t * $d;
+        if ($b > $n) break;
+        $a = floor($a / 10);
+        if ($b && $a + $b == $n)
+            return true;
+        $t = bcmod("$a", "10");
+    }
+    return false;
+}