Data commit

Task/Superpermutation-minimisation/C/superpermutation-minimisation.c

@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MAX 12
+char *super = 0;
+int pos, cnt[MAX];
+
+// 1! + 2! + ... + n!
+int fact_sum(int n)
+{
+	int s, x, f;
+	for (s = 0, x = 0, f = 1; x < n; f *= ++x, s += f);
+	return s;
+}
+
+int r(int n)
+{
+	if (!n) return 0;
+
+	char c = super[pos - n];
+	if (!--cnt[n]) {
+		cnt[n] = n;
+		if (!r(n-1)) return 0;
+	}
+	super[pos++] = c;
+	return 1;
+}
+
+void superperm(int n)
+{
+	int i, len;
+
+	pos = n;
+	len = fact_sum(n);
+	super = realloc(super, len + 1);
+	super[len] = '\0';
+
+	for (i = 0; i <= n; i++) cnt[i] = i;
+	for (i = 1; i <= n; i++) super[i - 1] = i + '0';
+
+	while (r(n));
+}
+
+int main(void)
+{
+	int n;
+	for (n = 0; n < MAX; n++) {
+		printf("superperm(%2d) ", n);
+		superperm(n);
+		printf("len = %d", (int)strlen(super));
+		// uncomment next line to see the string itself
+		// printf(": %s", super);
+		putchar('\n');
+	}
+
+	return 0;
+}