Data commit

Task/Modular-inverse/PowerShell/modular-inverse.psh

@@ -0,0 +1,23 @@
+function invmod($a,$n){
+        if ([int]$n -lt 0) {$n = -$n}
+        if ([int]$a -lt 0) {$a = $n - ((-$a) % $n)}
+
+	$t = 0
+	$nt = 1
+	$r = $n
+	$nr = $a % $n
+	while ($nr -ne 0) {
+		$q = [Math]::truncate($r/$nr)
+		$tmp = $nt
+		$nt = $t - $q*$nt
+		$t = $tmp
+		$tmp = $nr
+		$nr = $r - $q*$nr
+		$r = $tmp
+	}
+	if ($r -gt 1) {return -1}
+	if ($t -lt 0) {$t += $n}
+	return $t
+}
+
+invmod 42 2017