From 7a757657e6f2432e04258b898517791c48e99e02 Mon Sep 17 00:00:00 2001
From: Claudio Maggioni <claudio@maggioni.xyz>
Date: Fri, 11 Oct 2019 09:29:40 +0200
Subject: [PATCH] sortstrings: done with no libraries

---
 sortstrings/sortstrings.c     | 49 +++++++++++++++++++++++------------
 sortstrings/sortstrings_lib.c | 30 +++++++++++++++++++++
 2 files changed, 63 insertions(+), 16 deletions(-)
 create mode 100644 sortstrings/sortstrings_lib.c

diff --git a/sortstrings/sortstrings.c b/sortstrings/sortstrings.c
index eff4bb3..b0fd3b7 100644
--- a/sortstrings/sortstrings.c
+++ b/sortstrings/sortstrings.c
@@ -1,30 +1,47 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#define MAX_N 1000
+const unsigned int MAX_N = 1000;
 
-int compar(const void* string1, const void* string2) {
-	const char** s1 = (const char**) string1;
-	const char** s2 = (const char**) string2;
-	return strcmp(*s1, *s2);
+unsigned int c_strlen(const char* s) {
+	unsigned int i = 0;
+	for (; *s; s++) i++;
+	return i;
 }
 
-void sort_strings(const char* input, const char* output, unsigned int n) {
+unsigned int less_than(const char *s1, const char* s2) {
+	for(; *s1 == *s2 && *s1; s1++) s2++;
+	return (*s1 < *s2);
+}
+
+void insertion_sort(const char* strs[], unsigned int n) {
+	for (unsigned int i = 0; i < n-1; i++) {
+		for (unsigned int j = i+1; j > 0; j--) {
+			if (less_than(strs[j], strs[j-1])) {
+				const char* tmp = strs[j-1];
+				strs[j-1] = strs[j];
+				strs[j] = tmp;
+			} else {
+				break;
+			}
+		}
+	}
+}
+
+void sort_strings(const char* input, char* output, unsigned int n) {
 	const char* strings[MAX_N];
-	size_t i = 0;
-	size_t offset = 0;
+	unsigned int i = 0;
+	unsigned int offset = 0;
 	for (i = 0; i < n; i++) {
 		strings[i] = input + offset;
-		offset += strlen(input + offset) + 1; // + 1 for NUL
+		offset += c_strlen(input + offset) + 1; // + 1 for NUL
 	}
 
-	qsort(strings, n, sizeof(const char*), &compar);
+	insertion_sort(strings, n);
 
 	offset = 0;
 	for (i = 0; i < n; i++) {
-		const size_t len = strlen(strings[i]);
-		strncpy((char*) output + offset, (char*) strings[i], len + 1);
+		const unsigned int len = c_strlen(strings[i]);
+		for (unsigned int j = 0; j <= len; j++) {
+			output[offset + j] = strings[i][j];
+		}
 		offset += len + 1;
 	}
 }
-
diff --git a/sortstrings/sortstrings_lib.c b/sortstrings/sortstrings_lib.c
new file mode 100644
index 0000000..eff4bb3
--- /dev/null
+++ b/sortstrings/sortstrings_lib.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#define MAX_N 1000
+
+int compar(const void* string1, const void* string2) {
+	const char** s1 = (const char**) string1;
+	const char** s2 = (const char**) string2;
+	return strcmp(*s1, *s2);
+}
+
+void sort_strings(const char* input, const char* output, unsigned int n) {
+	const char* strings[MAX_N];
+	size_t i = 0;
+	size_t offset = 0;
+	for (i = 0; i < n; i++) {
+		strings[i] = input + offset;
+		offset += strlen(input + offset) + 1; // + 1 for NUL
+	}
+
+	qsort(strings, n, sizeof(const char*), &compar);
+
+	offset = 0;
+	for (i = 0; i < n; i++) {
+		const size_t len = strlen(strings[i]);
+		strncpy((char*) output + offset, (char*) strings[i], len + 1);
+		offset += len + 1;
+	}
+}
+