DnfSort.cpp

#include<bits/stdc++.h>
#include<iostream>

using namespace std;

void swap(int arr[],int a,int b){
    int temp=arr[a];
    arr[a]=arr[b];
    arr[b]=temp;
}

void dnf(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};

    dnf(arr,9);

    for(int i=0;i<9;i++){
        cout<<arr[i]<<" ";
    }
    return 0;
}