MergeSort.c

#include <stdio.h>
#include <stdlib.h>
void merge(int arr[],int l,int m,int r)
{
    int n1=m-l+1;
    int n2=r-m;
    int L[n1],R[n2];
    for(int i=0;i<n1;i++)
        L[i]=arr[l+i];
    for(int i=0;i<n2;i++)
        R[i]=arr[m+1+i];

    int i,j,k=l;
    i=j=0;

    while(i<n1 && j<n2)
    {
        if(L[i] <= R[j])
            arr[k++]=L[i++];
        else
            arr[k++]=R[j++];
    }
    while(i<n1)
        arr[k++]=L[i++];
    while(j<n2)
        arr[k++]=R[j++];
}


void mergeSort(int arr[],int l,int r)
{
    if(l>=r)
    return;

    int m=l+(r-l)/2;
    mergeSort(arr,l,m);
    mergeSort(arr,m+1,r);
    merge(arr,l,m,r);
}

void printArray(int A[],int size)
{
    for(int i=0;i<size;i++)
        printf("%d ",A[i]);
}

int main()
{
    int arr[]={12,11,13,5,6,7,3,52,516,34,123};
    int arr_size=sizeof(arr)/sizeof(arr[0]);
    printf("Given array is\n");
    printArray(arr,arr_size);
    mergeSort(arr,0,arr_size-1);
    printf("\nSorted array is\n");
    printArray(arr,arr_size);

    return 0;
}