From fb169134bf1a5ef03b9aeb258f130c3b0a6b6f3a Mon Sep 17 00:00:00 2001
From: David Phillips <david@sighup.nz>
Date: Thu, 5 Jan 2017 22:50:17 +1300
Subject: Add string permutation tool

---
 words-misc/permutations.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 words-misc/permutations.c

(limited to 'words-misc/permutations.c')

diff --git a/words-misc/permutations.c b/words-misc/permutations.c
new file mode 100644
index 0000000..4fafde0
--- /dev/null
+++ b/words-misc/permutations.c
@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* FIXME hacked together 6 months ago, not sure if finished */
+/* FIXME does duplicates */
+
+void swap_chr(char*, char*);
+void p(char *, size_t);
+
+int main(int argc, char **argv)
+{
+	if (argc != 2)
+	{
+		fprintf(stderr, "Usage: %s <word>\n", argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	p(argv[1], 0);
+
+	return 0;
+}
+
+void swap_chr(char *a, char *b) {
+	char t = *a;
+	*a = *b;
+	*b = t;
+}
+
+void p(char *string, size_t x)
+{
+	size_t i = 0;
+
+	if (x == strlen(string)) {
+		puts(string);
+		return;
+	}
+	for (i = 0; i < strlen(string); i++) {
+		swap_chr(&string[x], &string[i]);
+		p(string, x + 1);
+		swap_chr(&string[x], &string[i]);
+	}
+}
-- 
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