Sort algorithm

Merge Sort / Insertion Sort/ bubble sort/ selection sort

#include <iostream>using namespace std;int CUTOFF = 7;int arrAux[7];void swap(int *xp, int *yp){    int temp = *xp;    *xp = *yp;    *yp = temp;}// A function to implement bubble sortvoid bubbleSort(int arr[], int n){   int i, j;   for (i = 0; i < n-1; i++)              // Last i elements are already in place          for (j = 0; j < n-i-1; j++)            if (arr[j] > arr[j+1])              swap(&arr[j], &arr[j+1]);}void insertionSort(int arr[], int n){    for (int i = 0; i < n-1; i++)    {        for (int j = i+1; j > 0; j--)        {            if (arr[j] < arr[j-1])                swap(&arr[j], &arr[j-1]);        }    }}void selectionSort(int arr[], int n){        for (int i = 0; i < n; i++)    {        int min_index = i;        for (int j = i+1; j < n; j++)        {            if (arr[min_index] > arr[j])                min_index = j;        }        swap(&arr[i], &arr[min_index]);    }    }void merge(int* arr, int low, int mid, int high){    int p = low;    int q = mid+1;    for (int i = low; i <= high; i++)    {        arrAux[i] = arr[i];    }        for (int i = low; i <= high; i++)    {        if (p > mid)            arr[i] = arr[q++];        else if (q > high)            arr[i] = arrAux[p++];        else if (arrAux[p] > arrAux[q])        {            arr[i] = arrAux[q++];        }        else        {            arr[i] = arrAux[p++];        }    }}void Mergesort(int arr[], int low, int high){    // Imporvement #1 : using insertion sort for smaller array    if (high < low + CUTOFF - 1)    {        insertionSort(arr, high-1);    }    if (low >= high)        return;    int mid = (low + high)/2;    Mergesort(arr, low, mid);    Mergesort(arr, mid+1, high);    // Improvement #2 : Stop if it is alrady sorted    if (arr[mid+1] > arr[mid])        return;    merge(arr, low, mid, high);}/* Function to print an array */void printArray(int arr[], int size){    int i;    for (i=0; i < size; i++)        printf("%d ", arr[i]);    //printf("n");}int main(){    //int arr[] = {64, 34, 25, 12, 22, 11, 90};    int arr[] = {64, 34, 25, 12, 22, 11, 90, 2, 23, 39, 89, 88, 123, 10};    int n = sizeof(arr)/sizeof(arr[0]);    //selectionSort(arr, n);    Mergesort(arr, 0 , n-1);    printf("Sorted array: \n");    printArray(arr, n);    return 0;}

Merge sort variants ---- Count of inversion

#include <iostream>using namespace std;#define ARRARY_SIZE 10int aux[ARRARY_SIZE] = {};int count_inversion_merge(int* a, int first, int mid, int last){    int p1 = first;    int p2 = mid+1;    int count = 0;        for (int i = first; i <= last; i++)    {        aux[i] = a[i];    }    for (int i = first; i <= last; i++)    {        if (p1 > mid)        {            a[i] = aux[p2++];        }        else if (p2 > last)        {            a[i] = aux[p1++];        }        else if( aux[p1] > aux[p2])        {            a[i]  = aux[p2++];            count += (mid - p1 + 1);        }        else        {            a[i] = aux[p1++];        }    }    return count;}int count_inversion(int* a, int first, int last){    int counter = 0;    if (first >= last)        return 0;    int mid = (first + last) / 2;        int c1 = count_inversion(a, first, mid);    int c2 = count_inversion(a, mid+1, last);    int c3 = count_inversion_merge(a, first, mid, last);        return c1+c2+c3;}int main(){    int a[] = {9, 8 , 7, 6, 5, 4, 3, 2, 1, 10};    static_assert(sizeof(a)/sizeof(int) == ARRARY_SIZE, "The arrary size doesn't match");    int len = ARRARY_SIZE;    int inversion = count_inversion(a, 0, len-1);    int i;    for (i=0 ; i<len; i++)            printf("%d ", a[i]);    printf("\n");    printf("Total inversions : %d \n", inversion);                return 0;}