From 2fc1f7186e279940b622c4733b5b4a82f2299c9f Mon Sep 17 00:00:00 2001
From: Anlast <48757061+Anlast@users.noreply.github.com>
Date: Thu, 20 Jun 2019 20:12:38 +0100
Subject: [PATCH] Create binaryheap.c

Implemented BinaryHeap. Followed styling and conventions as in previous C files.
---
 c/src/binaryheap.c | 143 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 143 insertions(+)
 create mode 100644 c/src/binaryheap.c

diff --git a/c/src/binaryheap.c b/c/src/binaryheap.c
new file mode 100644
index 00000000..cd661d91
--- /dev/null
+++ b/c/src/binaryheap.c
@@ -0,0 +1,143 @@
+/*******************************************************************************
+ * File         : binaryheap.c
+ * Author(s)    : Andrii Lastivka <andriilastivka@gmail.com>
+ ******************************************************************************/
+
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+
+#include <binaryheap.h>
+
+#define binaryheap_left(i) (2*i + 1)
+#define binaryheap_right(i) (2*i + 2)
+#define binaryheap_parent(i) (i-1)/2
+
+static void resize(binaryheap_t *h) {
+
+    size_t realloc_size = 1;
+    
+    if (h->length > 0)
+        realloc_size = h->length * 2;
+
+    h->array = realloc(h->array, realloc_size * h->elem_size);
+
+    assert(h->array != NULL);
+
+    h->alloc_length = realloc_size;
+}
+
+void binaryheap_clear(binaryheap_t* h) {
+
+    assert((void *)h != NULL);
+
+    h->length       = 0;
+    h->alloc_length = 1;
+    h->array        = realloc(h->array, h->elem_size);
+
+    assert(h->array != NULL);
+}
+
+void binaryheap_add(binaryheap_t* h, void* elem) {	
+	size_t i, p;
+	void *temp;
+	
+	assert((void *)h != NULL);
+    assert(elem != NULL);
+
+    if (1 + h->length > h->alloc_length)
+        resize(h);
+	
+	memcpy((char *)h->array + (h->length)*h->elem_size, elem, h->elem_size);
+	
+	/* bubble up */
+	i = h->length;
+	p = binaryheap_parent(i);
+	temp = malloc(h->elem_size);
+	while(i > 0 && h->cmp((char *)h->array + (i * h->elem_size), (char *)h->array + (p * h->elem_size)) < 0)
+	{
+		
+		memcpy(temp, (char *)h->array + (i * h->elem_size), h->elem_size);
+		memcpy((char *)h->array + (i * h->elem_size), (char *)h->array + (p * h->elem_size), h->elem_size);
+		memcpy((char *)h->array + (p * h->elem_size), temp, h->elem_size);
+		i = p;
+		p = binaryheap_parent(i);
+		
+	}	
+	free(temp);
+	h->length++;
+}
+
+void binaryheap_dispose(binaryheap_t* h) {
+
+    assert((void *)h != NULL);
+    
+    free(h->array);
+}
+
+extern void binaryheap_init(binaryheap_t* h,
+                                  size_t elem_size,
+                                  int(*comparator)(void *, void *)){
+
+    assert((void *)h != NULL);
+    assert(h->elem_size > 0);
+
+    h->array = malloc(h->elem_size);
+
+    assert(h->array != NULL);
+
+    h->length       = 0;
+    h->alloc_length = 1;
+    h->elem_size    = elem_size;
+	h->cmp = comparator;
+}
+
+void binaryheap_remove(binaryheap_t* h,
+                                   void* elem_out)  {
+	int j, i, l, r;
+	void *temp;
+	
+	assert((void *)h != NULL);
+    assert(h->length > 0);
+
+    /* copy the removed data */
+    if (elem_out != NULL)
+        memcpy(elem_out, h->array, h->elem_size);
+
+	memcpy(h->array, (char *)h->array + (h->length-1)*h->elem_size, h->elem_size);
+	h->length--;
+    /* resize if necessary */
+    if (h->length * 3 < h->alloc_length)
+        resize(h);
+	
+	/* trickle down */
+	i = 0;
+	temp = malloc(h->elem_size);
+	while(i >= 0)
+	{
+		j = -1;
+		r = binaryheap_right(i);
+		l = binaryheap_left(i);
+		if(r < h->length && h->cmp((char *)h->array + (r * h->elem_size), (char *)h->array + (i * h->elem_size)) < 0)
+		{
+			if(h->cmp((char *)h->array + (l * h->elem_size), (char *)h->array + (r * h->elem_size)) < 0)
+				j = l;
+			else 
+				j = r;
+		}
+		else
+		{
+			if(l < h->length && h->cmp((char *)h->array + (l * h->elem_size), (char *)h->array + (i * h->elem_size)) < 0)
+				j = l;
+		}
+		if(j >= 0)
+		{
+			memcpy(temp, (char *)h->array + (i * h->elem_size), h->elem_size);
+			memcpy((char *)h->array + (i * h->elem_size), (char *)h->array + (j * h->elem_size), h->elem_size);
+			memcpy((char *)h->array + (j * h->elem_size), temp, h->elem_size);
+		}
+		i = j;
+	}
+	
+	free(temp);
+}