MinHeap

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <bits/stdc++.h>
using namespace std;

class Heap
{
public:
    vector<int> v;
    int heapsize;
    Heap()
    {
        v.push_back(INT_MAX);
        heapsize = 0;
    }
    int parent(int i)
    {
        return floor(i/2);
    }
    int left(int i)
    {
        return 2*i;
    }
    int right(int i)
    {
        return 2*i+1;
    }
    void buildMinHeap();
    void minHeapify(int i);
    void increaseKey(int i,int value);
    void insertKey(int value);
    int findIndex(int i,int value);
    int extractMin();
    bool isEmpty();
    int _min(){return v[1];}
    void _clear(){v.clear(); v.push_back(INT_MAX);heapsize = 0;}

};
void Heap::buildMinHeap()
{
    for(int i = heapsize/2; i >= 1; i--)
    {
        minHeapify(i);
    }
}
void Heap::minHeapify(int i)
{
    int l = left(i);
    int r = right(i);
    int smallest;
    if(l <= heapsize && v[l] < v[i])
    {
        smallest = l;
    }
    else
    {
        smallest = i;
    }
    if(r <= heapsize && v[r] < v[smallest])
    {
        smallest = r;
    }
    if(smallest != i)
    {
        swap(v[smallest],v[i]);
        minHeapify(smallest);
    }
}
void Heap::increaseKey(int i, int value)
{
    v[i] = value;
    while(i > 1 && v[parent(i)] > v[i])
    {
        swap(v[parent(i)],v[i]);
        i = parent(i);
    }
}
void Heap::insertKey(int value)
{
    v.push_back(INT_MAX);
    heapsize++;
    increaseKey(heapsize,value);
}
int Heap::extractMin()
{
    if(heapsize < 1)
        return -1;
    int _min = v[1];
    v[1] = v[heapsize];
    heapsize--;
    minHeapify(1);
    return _min;

}
int Heap::findIndex(int i, int value)
{
    int tmpindex;
    // cout << i << " " << heapsize << endl;
    if(v[i] == value)
        return i;
    else if(2*i > heapsize)
        return -1;
    else if((tmpindex = findIndex(2*i,value)) > 0)
    {
        return tmpindex;
    }
    else if(2*i+1 > heapsize)
    {
        return -1;
    }
    else
    {
        return findIndex(2*i+1,value);
    }
    return -1;
}
bool Heap::isEmpty()
{
    if(heapsize == 0)
        return true;
    return false;
}
int main() {
    Heap h;
    h.insertKey(3);
//    cout << h.heapsize << endl;
    h.insertKey(2);
    h.insertKey(1);
    while(!h.isEmpty())
    {
        cout << h.extractMin() << " ";
    }
    cout << endl;
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    return 0;
}