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6.sortHeap.cpp
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6.sortHeap.cpp
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// time complexity: n log n
// in-place sorting
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
//int arr[]={13,-3,-25,20,-3,-16,-23,18,20,-7,12,-5,-22,15,-4,7};
int arr[]={ 2, 1, 13, 5, 6, 7 };
void display(int size){
int i;
for(i=0;i<size;i++){
cout<<arr[i]<<" ";
}
cout<<"\n";
}
void swap(int *a, int *b){
int temp;
temp=*a;
*a=*b;
*b=temp;
}
int parent(int i){ return floor(i/2);}
int left(int i){ return 2*i;}
int right(int i){ return ((2*i)+1);}
//maintain heap property
void heapify(int size, int i)
{
int largest; // Initialize largest for/as root
int l = left(i); // left = 2*i + 1
int r = right(i); // right = 2*i + 2
// If left child is larger than root
if (l < size && arr[l] > arr[i]){
largest = l;
}
else{
largest = i;
}
// If right child is larger than largest so far
if (r < size && arr[r] > arr[largest])
largest = r;
// If largest is not root
if (largest != i) {
swap(arr[i], arr[largest]);
// Recursively heapify the affected sub-tree
heapify(size, largest);
}
}
// main function to do heap sort
void heapSort(int size)
{
// Build heap (rearrange array)
for (int i = size / 2 - 1; i >= 0; i--)
heapify(size, i);
// One by one extract an element from heap
for (int i = size - 1; i >= 0; i--) {
// Move current root to end
swap(arr[0], arr[i]);
// call max heapify on the reduced heap
heapify(i, 0);
display(size);
}
}
int main(){
int size = sizeof(arr)/sizeof(arr[0]);
heapSort(size);
return 0;
}