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github-actions 2020-06-20 18:34:51 +00:00
parent e464ddac36
commit 97bf410b36
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52
sorting/heap_sort.cpp
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@ -8,24 +8,24 @@
* \author [Ayaan Khan](http://github.com/ayaankhan98)
*
* \details
* heapsort is a comparison-based sorting algorithm.
* Heapsort can be thought of as an improved selection sort:
* like selection sort, heapsort divides its input into a sorted
* and an unsorted region, and it iteratively shrinks the unsorted
* region by extracting the largest element from it and inserting
* it into the sorted region. Unlike selection sort,
* heapsort does not waste time with a linear-time scan of the
* unsorted region; rather, heap sort maintains the unsorted region
* in a heap data structure to more quickly find the largest element
* heapsort is a comparison-based sorting algorithm.
* Heapsort can be thought of as an improved selection sort:
* like selection sort, heapsort divides its input into a sorted
* and an unsorted region, and it iteratively shrinks the unsorted
* region by extracting the largest element from it and inserting
* it into the sorted region. Unlike selection sort,
* heapsort does not waste time with a linear-time scan of the
* unsorted region; rather, heap sort maintains the unsorted region
* in a heap data structure to more quickly find the largest element
* in each step.
*
*
* Time Complexity - O(nlog(n))
*
*/
#include <iostream>
/**
*
*
* Utility Lambda function to print the array after
* sorting.
*
@ -33,25 +33,24 @@
* @param sz size of array
*
*/
auto printArray = [] (int *arr, int sz) {
for (int i = 0 ; i < sz ; i++)
std::cout << arr[i] <<" ";
auto printArray = [](int *arr, int sz) {
for (int i = 0; i < sz; i++) std::cout << arr[i] << " ";
std::cout << "\n";
};
/**
*
* The heapify procedure can be thought of as building a heap from
* the bottom up by successively sifting downward to establish the
* heap property.
*
* The heapify procedure can be thought of as building a heap from
* the bottom up by successively sifting downward to establish the
* heap property.
*
* @param arr array be to sorted
* @param
* @param
*/
void(*heapify)(int *arr, int n, int i) = [] (int *arr, int n, int i) {
void (*heapify)(int *arr, int n, int i) = [](int *arr, int n, int i) {
int largest = i;
int l = 2*i + 1;
int r = 2*i + 2;
int l = 2 * i + 1;
int r = 2 * i + 2;
if (l < n && arr[l] > arr[largest])
largest = l;
@ -73,11 +72,10 @@ void(*heapify)(int *arr, int n, int i) = [] (int *arr, int n, int i) {
* @param n size of array
*
*/
auto heapSort = [] (int *arr, int n) {
for (int i = n-1 ; i >= 0; i--)
heapify(arr, n, i);
auto heapSort = [](int *arr, int n) {
for (int i = n - 1; i >= 0; i--) heapify(arr, n, i);
for (int i = n-1 ; i >= 0; i--) {
for (int i = n - 1; i >= 0; i--) {
std::swap(arr[0], arr[i]);
heapify(arr, i, 0);
}
@ -88,7 +86,7 @@ int main() {
int arr[] = {-10, 78, -1, -6, 7, 4, 94, 5, 99, 0};
int sz = sizeof(arr) / sizeof(arr[0]); // sz - size of array
printArray(arr, sz); // displaying the array before sorting
heapSort(arr, sz); // calling heapsort to sort the array
heapSort(arr, sz); // calling heapsort to sort the array
printArray(arr, sz); // display array after sorting
return 0;
}