mirror of https://github.com/TheAlgorithms/C
98 lines
2.2 KiB
C
98 lines
2.2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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/*Displays the array, passed to this method*/
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void display(int arr[], int n)
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{
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int i;
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for (i = 0; i < n; i++)
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{
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printf("%d ", arr[i]);
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}
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printf("\n");
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}
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/*Swap function to swap two values*/
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void swap(int *first, int *second)
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{
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int temp = *first;
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*first = *second;
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*second = temp;
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}
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/*Partition method which selects a pivot
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and places each element which is less than the pivot value to its left
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and the elements greater than the pivot value to its right
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arr[] --- array to be partitioned
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lower --- lower index
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upper --- upper index
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*/
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int partition(int arr[], int lower, int upper)
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{
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int i = (lower - 1);
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int pivot = arr[upper]; // Selects last element as the pivot value
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int j;
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for (j = lower; j < upper; j++)
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{
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if (arr[j] <= pivot)
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{ // if current element is smaller than the pivot
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i++; // increment the index of smaller element
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swap(&arr[i], &arr[j]);
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}
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}
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swap(&arr[i + 1], &arr[upper]); // places the last element i.e, the pivot
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// to its correct position
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return (i + 1);
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}
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/*This is where the sorting of the array takes place
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arr[] --- Array to be sorted
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lower --- Starting index
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upper --- Ending index
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*/
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void quickSort(int arr[], int lower, int upper)
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{
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if (upper > lower)
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{
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// partitioning index is returned by the partition method , partition
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// element is at its correct poition
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int partitionIndex = partition(arr, lower, upper);
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// Sorting elements before and after the partition index
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quickSort(arr, lower, partitionIndex - 1);
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quickSort(arr, partitionIndex + 1, upper);
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}
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}
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int main()
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{
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int n;
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printf("Enter size of array:\n");
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scanf("%d", &n); // E.g. 8
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printf("Enter the elements of the array\n");
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int i;
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int *arr = (int *)malloc(sizeof(int) * n);
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for (i = 0; i < n; i++)
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{
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scanf("%d", &arr[i]);
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}
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printf("Original array: ");
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display(arr, n); // Original array : 10 11 9 8 4 7 3 8
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quickSort(arr, 0, n - 1);
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printf("Sorted array: ");
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display(arr, n); // Sorted array : 3 4 7 8 8 9 10 11
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getchar();
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return 0;
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}
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