DNF_sort.cpp

/*
----Dutch National Flag algorithm
----this algorithm is helpfull is sorting 0,1,2
*/
#include<iostream>
using namespace std;
void swap(int arr[],int i,int j)
{
    int temp=arr[i];
    arr[i]=arr[j];
    arr[j]=temp;
}
void dnssort(int arr[],int n)
{
    int low=0;
    int mid=0;
    int high=n-1;

while(mid<=high)
{
    if (arr[mid]==0)
    {
        swap(arr,low,mid);
        low++;
        mid++;
    }
    else if(arr[mid]==1)
    {
        mid++;
    }
    else{
        swap(arr,mid,high);
        high--;
    }
    
}
}
int main()
{
    int arr[]={1,0,2,1,0,1,2,1,2};
    dnssort(arr,9);
    for (int i = 0; i <9; i++)
    {
        cout<<arr[i]<<" ";
    }

    return 0;
    
}