Add 7-1

semester3/pset3/7-1-Binary-Heap.c

@@ -0,0 +1,108 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct heap {
+  int* arr;
+  int capacity;
+  int size;
+} heap;
+
+heap* newHeap(int size) {
+  heap* new = malloc(sizeof(heap));
+
+  new->arr = malloc(sizeof(int) * size);
+
+  new->size = 0;
+  new->capacity = size;
+
+  return new;
+}
+
+void swap(int* l, int* r) {
+  int tmp = *r;
+  *r = *l;
+  *l = tmp;
+}
+
+int max(int l, int r) {
+  return (l > r) ? l : r;
+}
+
+int parent(int i) {
+  return (i - 1) / 2;
+}
+
+int left (int i) {
+  return i * 2 + 1;
+}
+
+int right (int i) {
+  return i * 2 + 2;
+}
+
+void insert(heap* h, int val) {
+  int i = h->size++;
+
+  h->arr[i] = val;
+
+  while (i != 0 && h->arr[i] < h->arr[parent(i)]) {
+    swap(&h->arr[i], &h->arr[parent(i)]);
+    i = parent(i);
+  }
+}
+
+void heapify(heap * h, int i) {
+  int smallest = i;
+  int l = left(i);
+  int r = right(i);
+
+  // comparing size is important!
+  if (l < h->size && h->arr[smallest] > h->arr[l]) {
+    smallest = l;
+  }
+  if (r < h->size && h->arr[smallest] > h->arr[r]) {
+    smallest = r;
+  }
+
+  if (smallest != i) {
+    swap(&h->arr[smallest], &h->arr[i]);
+    heapify(h, smallest);
+  }
+}
+
+void buildHeap(heap* h) {
+  int start = h->size / 2 - 1;
+
+  while (start >= 0) {
+    heapify(h, start--);
+  }
+}
+
+void print(int* array, int size) {
+  for (int i = 0; i < size - 1; i++) {
+    printf("%d,", array[i]);
+  }
+  printf("%d\n", array[size - 1]);
+}
+
+int main(void) {
+  int size;
+  scanf("%d", &size);
+
+  int tmp;
+  heap* h1 = newHeap(size);
+  heap* h2 = newHeap(size);
+  h2->size = size;
+
+  for (int i = 0; i < size; i++) {
+    scanf("%d,", &tmp);
+    h2->arr[i] = tmp;
+    insert(h1, tmp);
+  }
+
+  buildHeap(h2);
+  print(h1->arr, size);
+  print(h2->arr, size);
+
+  return 0;
+}