Quicksort Algorithm Project Report

Quickselect algorithm implementation A project report submitted in partial fulfillment of the requirements of Algorithms Design Course (ICS353) for the completion of degree of Bachelor of Science in Computer Engineering

The Computer Science Department
King Fahd University of Petroleum and Minerals
January, 2011
ABSTRACT
Sorting and selection is widely used by computer applications intermediary to finish tasks like searching. QUICKSELECT algorithm is known to be among fastest selection algorithms. It has linear time as average expected time to select. This report shows QUICKSELECT algorithm implemented with sample output provided.

INTRODUCTION
This report shows implementation of QUICKSELECT algorithm using C language on Linux platform. The code represents some algorithms mentioned in “Algorithms Design Techniques and Analysis” which is the textbook of ICS353 course.

METHODOLOGY
Algorithms: SPLIT and QUICKSELECT have been C implemented on Linux platform. Then, corresponding functions to finish testing of robustness of the implementation have been implemented. Functions are: swap(),printlist(), and main().
Function: split int split(int list[], int low, int high){ int i, j, x, w; i = low; x = list[low]; for (j = low + 1; j<= high; j++){ if (list[j] <= x) { i++; if (i != j) swap(&list[i], &list[j]); } } swap(&list[low], &list[i]); w = i; return w;
}
Function: quicksort void quicksort(int list[], int low, int high){ int w; if (low < high){ w = split(list, low, high); quicksort(list, low, w-1); quicksort(list, w+1, high); }
}
Function: swap void swap(int *x,int *y)
{
int temp; temp = *x; *x = *y; *y = temp;
}

Function: printlist void printlist(int list[],int high){ int i; for(i=0;i<high;i++) printf("%d\t",list[i]);
}
Function: quickselect int quickselect(int numbers[], int low, int high, int rank) { if (low == high)