Question

Implement in C ONLY the heapSort algorithm discussed in class. For the BUILDHEAP procedure use the bottom-up approach. Verify the correctness of your heapsort program on arrays of small size (10’s of elements) and compare the running time of your heapsort program with your earlier implementation of the quicksort program on large arrays (100’s of elements)

Answer 1

#include<stdio.h>
#include <time.h>
#include<stdlib.h>
void heapsort(int[],int);
void heapify(int[],int);
void adjust(int[],int);
//driver program
main()
{
int n,i,a[500];
clock_t start, end;
double time_used=0;

printf("\nEnter the number of elements to sort:");
scanf("%d",&n);
printf("\nEnter %d elements:",n);
for (i=0;i<n;i++)
{
   printf("\n Enter %d element",i+1);
   scanf("%d",&a[i]);
}
/* Recording the starting clock tick.*/
start = clock();
heapsort(a,n);
// Recording the end clock tick.
end = clock();
  
// Calculating total time taken by the program.
time_used = (double)(end - start) / (double)(CLOCKS_PER_SEC);
printf("Time required for sort %d elements is %lf secs.",n,time_used);
printf("\nThe Sorted Elements Are:\n");
for (i=0;i<n;i++)
printf(" %d ",a[i]);
//loop to generate 100 numbers and sort them using heapsort
for(i=0;i<100;i++)
{
    a[i]= rand() % 500 +1;
}
time_used=0;
/* Recording the starting clock tick.*/
start = clock();
heapsort(a,100);
// Recording the end clock tick.
end = clock();

// Calculating total time taken by the program.
time_used = (double)(end - start) / (double)(CLOCKS_PER_SEC);
printf("\nTime required for sort 100 elements is %lf secs.",time_used);
printf("\nThe Sorted Elements Are:\n");
for (i=0;i<100;i++)
printf("\t%d",a[i]);
printf("\n");
}

//heapsort() method

void heapsort(int a[],int n)
{
int i,t;
heapify(a,n); //call to heapify method
for (i=n-1;i>0;i--) {
t = a[0]; //perform swap operation
a[0] = a[i];
a[i] = t;
adjust(a,i);
}
}
//heapify() method
void heapify(int a[],int n) {
int k,i,j,item;
for (k=1;k<n;k++) {
item = a[k];
i = k;
j = (i-1)/2;
while((i>0)&&(item>a[j])) {
a[i] = a[j];
i = j;
j = (i-1)/2;
}
a[i] = item;
}
}
//adjust() methjod
void adjust(int a[],int n) {
int i,j,item;
j = 0;
item = a[j];
i = 2*j+1;
while(i<=n-1) {
if(i+1 <= n-1)
if(a[i] <a[i+1])
i++;
if(item<a[i]) {
a[j] = a[i];
j = i;
i = 2*j+1;
} else
break;
}
a[j] = item;
}

OUTPUT