Data commit

Task/Happy-numbers/C/happy-numbers-1.c

@@ -0,0 +1,33 @@
+#include <stdio.h>
+
+#define CACHE 256
+enum { h_unknown = 0, h_yes, h_no };
+unsigned char buf[CACHE] = {0, h_yes, 0};
+
+int happy(int n)
+{
+	int sum = 0, x, nn;
+	if (n < CACHE) {
+		if (buf[n]) return 2 - buf[n];
+		buf[n] = h_no;
+	}
+
+	for (nn = n; nn; nn /= 10) x = nn % 10, sum += x * x;
+
+	x = happy(sum);
+	if (n < CACHE) buf[n] = 2 - x;
+	return x;
+}
+
+int main()
+{
+	int i, cnt = 8;
+	for (i = 1; cnt || !printf("\n"); i++)
+		if (happy(i)) --cnt, printf("%d ", i);
+
+	printf("The %dth happy number: ", cnt = 1000000);
+	for (i = 1; cnt; i++)
+		if (happy(i)) --cnt || printf("%d\n", i);
+
+	return 0;
+}

Task/Happy-numbers/C/happy-numbers-2.c

@@ -0,0 +1,31 @@
+#include <stdio.h>
+
+int dsum(int n)
+{
+	int sum, x;
+	for (sum = 0; n; n /= 10) x = n % 10, sum += x * x;
+	return sum;
+}
+
+int happy(int n)
+{
+	int nn;
+	while (n > 999) n = dsum(n); /* 4 digit numbers can't cycle */
+	nn = dsum(n);
+	while (nn != n && nn != 1)
+		n = dsum(n), nn = dsum(dsum(nn));
+	return n == 1;
+}
+
+int main()
+{
+	int i, cnt = 8;
+	for (i = 1; cnt || !printf("\n"); i++)
+		if (happy(i)) --cnt, printf("%d ", i);
+
+	printf("The %dth happy number: ", cnt = 1000000);
+	for (i = 1; cnt; i++)
+		if (happy(i)) --cnt || printf("%d\n", i);
+
+	return 0;
+}