Quicksort & Mergesort With C
Karl Xavier
Posted on December 14, 2023
#include <stdio.h>
// Function to swap two elements
void swap(int* a, int* b) {
int temp = *a;
*a = *b;
*b = temp;
}
// Function to partition array for quicksort
int partition(int arr[], int low, int high) {
int pivot = arr[high];
int i = low - 1;
for (int j = low; j <= high - 1; j++) {
if (arr[j] < pivot) {
i++;
swap(&arr[i], &arr[j]);
}
}
swap(&arr[i + 1], &arr[high]);
return i + 1;
}
// Quicksort algorithm
void quicksort(int arr[], int low, int high) {
if (low < high) {
int pi = partition(arr, low, high);
quicksort(arr, low, pi - 1);
quicksort(arr, pi + 1, high);
}
}
// Function to merge two subarrays for mergesort
void merge(int arr[], int left, int mid, int right) {
int n1 = mid - left + 1;
int n2 = right - mid;
int leftArr[n1];
int rightArr[n2];
for (int i = 0; i < n1; i++) {
leftArr[i] = arr[left + i];
}
for (int j = 0; j < n2; j++) {
rightArr[j] = arr[mid + 1 + j];
}
int i = 0, j = 0, k = left;
while (i < n1 && j < n2) {
if (leftArr[i] <= rightArr[j]) {
arr[k] = leftArr[i];
i++;
} else {
arr[k] = rightArr[j];
j++;
}
k++;
}
while (i < n1) {
arr[k] = leftArr[i];
i++;
k++;
}
while (j < n2) {
arr[k] = rightArr[j];
j++;
k++;
}
}
// Mergesort algorithm
void mergesort(int arr[], int left, int right) {
if (left < right) {
int mid = (left + right) / 2;
mergesort(arr, left, mid);
mergesort(arr, mid + 1, right);
merge(arr, left, mid, right) ;
}
}
// Function to print an array
void printArray(int arr[], int size) {
for (int i = 0; i < size; i++) {
printf("%d ", arr[i]);
}
printf("\n");
}
int main() {
int arr1[] = {10, 7, 8, 9, 1, 5};
int n1 = sizeof(arr1) / sizeof(arr1[0]);
printf("Original array: ");
printArray(arr1, n1);
quicksort(arr1, 0, n1 - 1);
printf("Array after QuickSort: ");
printArray(arr1, n1);
int arr2[] = {10, 7, 8, 9, 1, 5};
int n2 = sizeof(arr2) / sizeof(arr2[0]);
printf("Original array: ");
printArray(arr2, n2);
mergesort(arr2, 0, n2 - 1);
printf("Array after MergeSort: ");
printArray(arr2, n2);
return 0;
}
💖 💪 🙅 🚩
Karl Xavier
Posted on December 14, 2023
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