Data commit

Task/Non-continuous-subsequences/C/non-continuous-subsequences-1.c

@@ -0,0 +1,20 @@
+#include <assert.h>
+#include <stdio.h>
+
+int main(int c, char **v)
+{
+	unsigned int n = 1 << (c - 1), i = n, j, k;
+	assert(n);
+
+	while (i--) {
+		if (!(i & (i + (i & -(int)i)))) // consecutive 1s
+			continue;
+
+		for (j = n, k = 1; j >>= 1; k++)
+			if (i & j) printf("%s ", v[k]);
+
+		putchar('\n');
+	}
+
+	return 0;
+}

Task/Non-continuous-subsequences/C/non-continuous-subsequences-2.c

@@ -0,0 +1,25 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void binprint(unsigned int n, unsigned int m)
+{
+	char c[sizeof(n) * 8 + 1];
+	int i = 0;
+	while (m >>= 1)	c[i++] = n & m ? '#' : '-';
+	c[i] = 0;
+	puts(c);
+}
+
+int main(int c, char **v)
+{
+	unsigned int n, gap, left, right;
+	if (c < 2 || ! (n = 1 << atoi(v[1]))) n = 16;
+
+	for (gap = 2; gap < n; gap <<= 1)
+		for (left = gap << 1; left < n; left |= left << 1)
+			for (right = 1; right < gap; right++)
+				binprint(left | right, n);
+
+	return 0;
+}

Task/Non-continuous-subsequences/C/non-continuous-subsequences-3.c

@@ -0,0 +1,51 @@
+#include <stdio.h>
+
+typedef unsigned char sint;
+enum states { s_blnk = 0, s_tran, s_cont, s_disj };
+
+/* Recursively look at each item in list, taking both choices of
+   picking the item or not.  The state at each step depends on prvious
+   pickings, with the state transition table:
+	blank + no pick -> blank
+	blank + pick -> contiguous
+	transitional + no pick -> transitional
+	transitional + pick -> disjoint
+	contiguous + no pick -> transitional
+	contiguous + pick -> contiguous
+	disjoint + pick -> disjoint
+	disjoint + no pick -> disjoint
+   At first step, before looking at any item, state is blank.
+   Because state is known at each step and needs not be calculated,
+   it can be quite fast.
+*/
+unsigned char tbl[][2] = {
+	{ s_blnk, s_cont },
+	{ s_tran, s_disj },
+	{ s_tran, s_cont },
+	{ s_disj, s_disj },
+};
+
+void pick(sint n, sint step, sint state, char **v, unsigned long bits)
+{
+	int i, b;
+	if (step == n) {
+		if (state != s_disj) return;
+		for (i = 0, b = 1; i < n; i++, b <<= 1)
+			if ((b & bits)) printf("%s ", v[i]);
+		putchar('\n');
+		return;
+	}
+
+	bits <<= 1;
+	pick(n, step + 1, tbl[state][0], v, bits); /* no pick */
+	pick(n, step + 1, tbl[state][1], v, bits | 1); /* pick */
+}
+
+int main(int c, char **v)
+{
+	if (c - 1 >= sizeof(unsigned long) * 4)
+		printf("Too many items");
+	else
+		pick(c - 1, 0, s_blnk, v + 1, 0);
+	return 0;
+}