From 6796489725e2e72a2886beaa48feae0cae2e2909 Mon Sep 17 00:00:00 2001
From: Eric Patrizio <epatrizio@mpns.fr>
Date: Tue, 25 Jan 2022 15:15:57 +0100
Subject: [PATCH] Add heap sort priority queue example

---
 .gitignore           |  2 ++
 Makefile             |  6 +++++-
 README.md            |  7 +++++--
 examples/sort/main.c | 39 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 51 insertions(+), 3 deletions(-)
 create mode 100644 examples/sort/main.c

diff --git a/.gitignore b/.gitignore
index 08e8dc9..8aa7837 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,6 +2,8 @@ cds
 cds_test
 intl
 !intl/
+sort
+!sort/
 /tests/lib/
 
 # vsc
diff --git a/Makefile b/Makefile
index d39e2ce..fd005b0 100644
--- a/Makefile
+++ b/Makefile
@@ -11,4 +11,8 @@ compile_test:
 
 compile_example_intl:
 	gcc -g -o intl -Wall -Wextra	\
-	src/vector.c src/hash_utils.c src/hash_map.c examples/intl/intl.c examples/intl/main.c
\ No newline at end of file
+	src/vector.c src/hash_utils.c src/hash_map.c examples/intl/intl.c examples/intl/main.c
+
+compile_example_sort:
+	gcc -g -o sort -Wall -Wextra	\
+	src/vector.c src/priority_queue.c examples/sort/main.c
\ No newline at end of file
diff --git a/README.md b/README.md
index 8c8988b..4af6435 100644
--- a/README.md
+++ b/README.md
@@ -51,7 +51,10 @@ Implementations are inspired by this [blog post](https://www.journaldev.com/3523
 Execute "make compile_test" and that's all!\
 I use the framework [ctestfmk](https://github.com/epatrizio/ctestfmk). Read the documentation for more informations.
 
-## Example
+## Examples
 
-In /example directory, you can find a complete application of HashMap data structure:\
+* In /examples/intl directory, there is a complete application of HashMap data structure:\
 A little internationalization component.
+
+* In /examples/sort directory, there is a classic and easy application of priority queue data structure:\
+The array heap sort. For simplicity, only the int type has been processed.
diff --git a/examples/sort/main.c b/examples/sort/main.c
new file mode 100644
index 0000000..ddb9e20
--- /dev/null
+++ b/examples/sort/main.c
@@ -0,0 +1,39 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "../../src/vector.h"
+#include "../../src/priority_queue.h"
+
+/*
+This implementation of heapsort is very easy and work well.
+But it requires 2 arrays : the initial array to sort and the temp priority queue array.
+It's possible to have a more efficient (in memory) implementation with only the initial array :
+    https://en.wikipedia.org/wiki/Heapsort
+*/
+void heap_sort(int a[], size_t size)
+{
+    int_priority_queue pq = int_priority_queue_create();
+
+    for (unsigned int i = 0 ; i < size ; i++)
+        int_priority_queue_push(pq, a[i]);
+
+    for (unsigned int i = 0 ; i < size ; i++)
+        a[i] = int_priority_queue_pop(pq);
+
+    int_priority_queue_destroy(pq);
+}
+
+int main()
+{
+    int a[] = { 0, 25, 32, 10, 1, 50, 20, 100, -1, 27, 28, 10, 3, 99, -10, -1, 110, 55, 75, -2, 0 };
+    size_t size = sizeof(a) / sizeof(int);
+
+    heap_sort(a,size);
+
+    for (unsigned int i = 0 ; i < size ; i++)
+        printf("%i:%i\n", i, a[i]);
+
+    return EXIT_SUCCESS;
+}