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Heap.h
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Heap.h
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#include <iostream>
using namespace std;
void swap(int *a, int *b)
{
int c = *a;
*a = *b;
*b = c;
}
class MinHeap
{
public:
int capacity;
int heap_size;
int *heap_data;
MinHeap(int capacity)
{
this->heap_size = 0;
this->capacity = capacity;
this->heap_data = new int[capacity];
}
int parent(int i)
{
return (i-1)/2;
}
int left(int i)
{
return (2*i + 1);
}
int right(int i)
{
return (2*i + 2);
}
int getMin()
{
return heap_data[0];
}
void Heapify(int i)
{
int l = left(i);
int r = right(i);
int smallest = i;
if (l < heap_size && heap_data[l] < heap_data[i])
{
smallest = l;
}
if (r < heap_size && heap_data[r] < heap_data[smallest])
{
smallest = r;
}
if (smallest != i)
{
swap(&heap_data[i], &heap_data[smallest]);
Heapify(smallest);
}
}
int pop_minimum()
{
if (heap_size <= 0)
{
return +999999999;
}
if (heap_size == 1)
{
heap_size--;
return heap_data[0];
}
int root = heap_data[0];
heap_data[0] = heap_data[heap_size-1];
heap_size--;
Heapify(0);
return root;
}
void decrease_item(int i, int new_val)
{
heap_data[i] = new_val;
while (i != 0 && heap_data[parent(i)] > heap_data[i])
{
swap(&heap_data[i], &heap_data[parent(i)]);
i = parent(i);
}
}
void delete_item(int i)
{
decrease_item(i, -999999999);
pop_minimum();
}
void insert_item(int k)
{
if (heap_size == capacity)
{
cout << "\nOverflow Error\n";
return;
}
heap_size++;
int i = heap_size - 1;
heap_data[i] = k;
while (i != 0 && heap_data[parent(i)] > heap_data[i])
{
swap(&heap_data[i], &heap_data[parent(i)]);
i = parent(i);
}
}
};