Initial data commit

Task/CUSIP/PHP/cusip.php

@@ -0,0 +1,39 @@
+function IsCusip(string $s) {
+    if (strlen($s) != 9) return false;
+    $sum = 0;
+    for ($i = 0; $i <= 7; $i++) {
+        $c = $s[$i];
+        if (ctype_digit($c)) {
+            // if character is numeric, get character's numeric value
+            $v = intval($c);
+        } elseif (ctype_alpha($c)) {
+            // if character is alphabetic, get character's ordinal position in alphabet
+            $position = ord(strtoupper($c)) - ord('A') + 1;
+            $v = $position + 9;
+        } elseif ($c == "*") {
+            $v = 36;
+        } elseif ($c == "@") {
+            $v = 37;
+        } elseif ($c == "#") {
+            $v = 38;
+        } else {
+            return false;
+        }
+        // is this character position even?
+        if ($i % 2 == 1) {
+            $v *= 2;
+        }
+        // calculate the checksum digit
+        $sum += floor($v / 10 ) + ( $v % 10 );
+    }
+    return ord($s[8]) - 48 == (10 - ($sum % 10)) % 10;
+}
+
+$cusips = array("037833100",
+                "17275R102",
+                "38259P508",
+                "594918104",
+                "68389X106",
+                "68389X105");
+
+foreach ($cusips as $cusip) echo $cusip . " -> " . (IsCusip($cusip) ? "valid" : "invalid") . "\n";