Add string permutation tool

2 files changed, 44 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 4db000d..00e3b3e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 words-misc/match_pool
+words-misc/permutations
 monty/monty
 *.o
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]);
+	}
+}