chore(C): add min and max heap (#386)

algorithms/C/README.md

@@ -38,6 +38,8 @@
 - [Max and Min Element Of Tree](tree/min-and-max-of-tree.c)
 - [Binary Search Tree](tree/binary-search-tree.c)
 - [Avl Tree](tree/avl-tree.c)
+- [Min Heap](tree/min-heap.c)
+- [Max Heap](tree/max-heap.c)
 
 ## Searching
 - [Binary Search](searching/Binary-search.c)

algorithms/C/tree/max-heap.c

@@ -0,0 +1,118 @@
+/*
+Max-Heap is a binary tree structure such that every node in the tree will be
+lesser or equal to the parent node. It is used when you need quick access to
+the largest number in the array.
+
+Time complexity to build the heap: O(n)
+Time complexity to remove max: O(log(n))
+Time complexity to remove all elements: O(n*log(n))
+*/
+
+#include <stdio.h>
+
+#include <stdlib.h>
+
+struct HEAP {
+  int * items, size, capacity;
+}* heap;
+
+void swap(int * a, int * b) {
+  int temp = * b;
+  * b = * a;
+  * a = temp;
+}
+
+void init(struct HEAP ** heap) {
+  * heap = (struct HEAP * ) malloc(sizeof(struct HEAP));
+  ( * heap) -> capacity = 2;
+  ( * heap) -> size = 0;
+  ( * heap) -> items = (int * ) malloc(sizeof(int) * ( * heap) -> capacity + 1);
+}
+
+void allocate(struct HEAP ** heap) {
+  ( * heap) -> capacity *= 2;
+  ( * heap) -> items = (int * ) realloc(( * heap) -> items, sizeof(int) * ( * heap) -> capacity + 1);
+}
+
+void heapify_up(struct HEAP ** heap, int size) {
+  if (size > 1) {
+    if (( * heap) -> items[size / 2] < ( * heap) -> items[size]) {
+      swap( & ( * heap) -> items[size / 2], & ( * heap) -> items[size]);
+      heapify_up(heap, size / 2);
+    }
+  }
+}
+
+void insert(struct HEAP ** heap, int val) {
+  if (( * heap) -> size == ( * heap) -> capacity) {
+    allocate(heap);
+  }
+  ( * heap) -> items[++( * heap) -> size] = val;
+  heapify_up(heap, ( * heap) -> size);
+}
+
+int child(struct HEAP * heap, int index) {
+  int left = index * 2;
+  int right = index * 2 + 1;
+
+  if (right > heap -> size) {
+    return left;
+  } else if (heap -> items[left] >= heap -> items[right]) {
+    return left;
+  }
+  return right;
+}
+
+void heapify_down(struct HEAP ** heap, int index) {
+  int childindex = child( * heap, index);
+  if (index * 2 <= ( * heap) -> size) {
+    if (( * heap) -> items[index] < ( * heap) -> items[childindex]) {
+      swap( & ( * heap) -> items[index], & ( * heap) -> items[childindex]);
+      heapify_down(heap, childindex);
+    }
+  }
+}
+
+void removemax(struct HEAP ** heap) {
+  swap( & ( * heap) -> items[1], & ( * heap) -> items[( * heap) -> size--]);
+  heapify_down(heap, 1);
+}
+
+void print(struct HEAP * heap) {
+  for (int i = 1; i <= heap -> size; i++) {
+    printf("%i ", heap -> items[i]);
+  }
+  printf("\n");
+}
+
+void deallocate(struct HEAP ** heap) {
+  free(( * heap) -> items);
+  free( * heap);
+}
+
+int main(void) {
+  init( & heap);
+
+  insert( & heap, 4);
+  insert( & heap, 10);
+  insert( & heap, 2);
+  insert( & heap, 22);
+  insert( & heap, 45);
+  insert( & heap, 18);
+
+  // Before removemax
+  print(heap);
+
+  removemax( & heap);
+
+  // After removemax
+  print(heap);
+  /*
+  	(before removemax)Output: 45 22 18 4 10 2
+  	(after removemax)Output: 22 10 18 4 2
+  */
+
+  deallocate( & heap);
+
+  return 0;
+}

algorithms/C/tree/min-heap.c

@@ -0,0 +1,118 @@
+/*
+Min-Heap is a binary tree structure such that every node in the tree will be
+lesser or equal to the child node. It is used when you need quick access to
+the smallest number in the array.
+
+Time complexity to build the heap: O(n)
+Time complexity to remove min: O(log(n))
+Time complexity to remove all elements: O(n*log(n))
+*/
+
+#include <stdio.h>
+
+#include <stdlib.h>
+
+struct HEAP {
+  int * items, size, capacity;
+}* heap;
+
+void swap(int * a, int * b) {
+  int temp = * b;
+  * b = * a;
+  * a = temp;
+}
+
+void init(struct HEAP ** heap) {
+  * heap = (struct HEAP * ) malloc(sizeof(struct HEAP));
+  ( * heap) -> capacity = 2;
+  ( * heap) -> size = 0;
+  ( * heap) -> items = (int * ) malloc(sizeof(int) * ( * heap) -> capacity + 1);
+}
+
+void allocate(struct HEAP ** heap) {
+  ( * heap) -> capacity *= 2;
+  ( * heap) -> items = (int * ) realloc(( * heap) -> items, sizeof(int) * ( * heap) -> capacity + 1);
+}
+
+void heapify_up(struct HEAP ** heap, int size) {
+  if (size > 1) {
+    if (( * heap) -> items[size / 2] > ( * heap) -> items[size]) {
+      swap( & ( * heap) -> items[size / 2], & ( * heap) -> items[size]);
+      heapify_up(heap, size / 2);
+    }
+  }
+}
+
+void insert(struct HEAP ** heap, int val) {
+  if (( * heap) -> size == ( * heap) -> capacity) {
+    allocate(heap);
+  }
+  ( * heap) -> items[++( * heap) -> size] = val;
+  heapify_up(heap, ( * heap) -> size);
+}
+
+int child(struct HEAP * heap, int index) {
+  int left = index * 2;
+  int right = index * 2 + 1;
+
+  if (right > heap -> size) {
+    return left;
+  } else if (heap -> items[left] <= heap -> items[right]) {
+    return left;
+  }
+  return right;
+}
+
+void heapify_down(struct HEAP ** heap, int index) {
+  int childindex = child( * heap, index);
+  if (index * 2 <= ( * heap) -> size) {
+    if (( * heap) -> items[index] > ( * heap) -> items[childindex]) {
+      swap( & ( * heap) -> items[index], & ( * heap) -> items[childindex]);
+      heapify_down(heap, childindex);
+    }
+  }
+}
+
+void removemin(struct HEAP ** heap) {
+  swap( & ( * heap) -> items[1], & ( * heap) -> items[( * heap) -> size--]);
+  heapify_down(heap, 1);
+}
+
+void print(struct HEAP * heap) {
+  for (int i = 1; i <= heap -> size; i++) {
+    printf("%i ", heap -> items[i]);
+  }
+  printf("\n");
+}
+
+void deallocate(struct HEAP ** heap) {
+  free(( * heap) -> items);
+  free( * heap);
+}
+
+int main(void) {
+  init( & heap);
+
+  insert( & heap, 4);
+  insert( & heap, 10);
+  insert( & heap, 2);
+  insert( & heap, 22);
+  insert( & heap, 45);
+  insert( & heap, 18);
+
+  // Before removemin
+  print(heap);
+
+  removemin( & heap);
+
+  // After removemin
+  print(heap);
+  /*
+  	(before removemin)Output:2 10 4 22 45 18
+  	(after removemin)Output: 4 10 18 22 45
+  */
+
+  deallocate( & heap);
+
+  return 0;
+}