A New Look at Worst Case Complexity: A Statistical Approach

Algorithm 3

The “C” code implementation of the randomized quick sort.

// System specification:

//Processor: Intel(R) Core (TM) i5-3210 CPU @ 2.50 GHz 2.50 GHz

// Installed Memory (RAM): 4.00 GB

// System Type: 64-bitoperating system

int main (int argc, char *argv)

{

 ⋯⋯⋯⋯⋯⋯⋯⋯

 quicksort( A, low, high);

 ⋯⋯⋯⋯⋯⋯⋯⋯

}

void quicksort(int A, int low, int high)

{

 int p;

 if(low>=high)

 return;

 p=Random_partition(A,low,high);

 quicksort(A,low,p-1);

 quicksort(A,p+1,high);

}

int Random_partition(int A, int low, int high)

{

 int temp,key,i,j;

 key = A[rand()%(high-low+1)+low];

 i=low+1;

 j=high;

 while(i <= j)

 {

    while(A[i] <= key && i<=j)

    {

    i++;

    }

    while(A[j] > key && i <= j)

    {

    j- -;

    }

    if(i <= j)

    {

     temp=A[i];

     A[i]=A[j];

     A[j]=temp;

    }

 }

  A[low]=A[j];

  A[j]=key;

  return(j);

}