Data commit

Task/Digital-root/C/digital-root.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+
+int droot(long long int x, int base, int *pers)
+{
+	int d = 0;
+	if (pers)
+		for (*pers = 0; x >= base; x = d, (*pers)++)
+			for (d = 0; x; d += x % base, x /= base);
+	else if (x && !(d = x % (base - 1)))
+			d = base - 1;
+
+	return d;
+}
+
+int main(void)
+{
+	int i, d, pers;
+	long long x[] = {627615, 39390, 588225, 393900588225LL};
+
+	for (i = 0; i < 4; i++) {
+		d = droot(x[i], 10, &pers);
+		printf("%lld: pers %d, root %d\n", x[i], pers, d);
+	}
+
+	return 0;
+}