Quicksort in C

A from-scratch implementation of the Quicksort algorithm in C using the Lomuto partition scheme.

Build and Run

gcc -Wall -Wextra -std=c99 -o quicksort quicksort.c
./quicksort

Example Output

Unsorted: 10 7 8 9 1 5 3 4 2 6
Sorted:   1 2 3 4 5 6 7 8 9 10

Complexity

Case	Time	Space
Best	O(n log n)	O(log n)
Average	O(n log n)	O(log n)
Worst	O(n²)	O(n)

The worst case occurs when the pivot is consistently the smallest or largest element (e.g. an already-sorted array).