Power set: Difference between revisions

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 =={{header|C}}==
-<lang c>#include <limits.h>
+<lang c>#include <stdio.h>
-#include <stdio.h>
-#include <stdlib.h>
+struct node {
-static void powerset(int argc, char** argv)
+	char *s;
-{
+	struct node* prev;
-    unsigned int i, j, bits, i_max = 1U << argc;
+};
+void powerset(char **v, int n, struct node *up)
-    if (argc >= sizeof(i) * CHAR_BIT) {
+{
-        fprintf(stderr, "Error: set too large\n");
+	struct node me;
-        exit(1);
-    }
+	if (!n) {
-    for (i = 0; i < i_max ; ++i) {
+		putchar('[');
-        printf("{");
+		while (up) {
-        for (bits = i, j = 0; bits; bits >>= 1, ++j) {
+			printf(" %s", up->s);
-            if (bits & 1)
+			up = up->prev;
-                printf(bits > 1 ? "%s, " : "%s", argv[j]);
+		}
-        }
-        printf("}\n");
+		puts(" ]");
+	} else {
-    }
+		me.s = *v;
+		me.prev = up;
+		powerset(v + 1, n - 1, up);
+		powerset(v + 1, n - 1, &me);
+	}
 }
-int main(int argc, char* argv[])
+int main(int argc, char **argv)
 {
-    powerset(argc - 1, argv + 1);
+	powerset(argv + 1, argc - 1, 0);
-    return 0;
+	return 0;
-}</lang>output<lang>% ./a.out 1 2 3 4
+}</lang>
-{}
+{{out}}
+<pre>
-{1}
+% ./a.out 1 2 3
-{2}
+[ ]
-{1, 2}
+[ 3 ]
-{3}
+[ 2 ]
-{1, 3}
-{2, 3}
+[ 3 2 ]
-{1, 2, 3}
+[ 1 ]
+[ 3 1 ]
-{4}
-{1, 4}
+[ 2 1 ]
+[ 3 2 1 ]
-{2, 4}
+</pre>
-{1, 2, 4}
-{3, 4}
-{1, 3, 4}
-{2, 3, 4}
-{1, 2, 3, 4}</lang>
 =={{header|C++}}==