Quick Sort Code
Sort an array A using Quick Sort.
Change in the input array itself. So no need to return or print anything.
Input format :
Output format :
Constraints :
1 <= n <= 1000
Sample Input:
Sample Output:
Like Merge Sort, QuickSort is a Divide and Conquer algorithm. It picks an element as pivot and partitions the given array around the picked pivot. There are many different versions of quickSort that pick pivot in different ways.
- Always pick first element as pivot.
- Always pick last element as pivot (implemented below)
- Pick a random element as pivot.
- Pick median as pivot.
The key process in quickSort is partition(). Target of partitions is, given an array and an element x of array as pivot, put x at its correct position in sorted array and put all smaller elements (smaller than x) before x, and put all greater elements (greater than x) after x. All this should be done in linear time.
public class Solution {
private static int findIndex(int[] input,int low,int high,int pivot)
{
int pI = low;
int itr=low;
while(itr<=high)
{
if(input[itr]<=pivot)
{
int temp = input[itr];
input[itr] = input[pI];
input[pI] = temp;
itr++;
pI++;
}
else
{
itr++;
}
}
return pI-1;
}
private static void quickSort(int[] input,int low ,int high)
{
if(low>=high)
{
return;
}
int pivot = input[high];
int pivotIndex = findIndex(input,low,high,pivot);
quickSort(input,low,pivotIndex-1);
quickSort(input,pivotIndex +1,high);
}
public static void quickSort(int[] input) {
int low =0;
int high = input.length-1;
quickSort(input,low,high);
}
}
Subscribe to:
Post Comments
(
Atom
)
No comments :
Post a Comment