DutchAlgo.cpp

// C++ program to sort an array 
// with 0, 1 and 2 in a single pass 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to sort the input array, 
// the array is assumed 
// to have values in {0, 1, 2} 
void sort012(int a[], int arr_size) 
{ 
    int lo = 0; 
    int hi = arr_size - 1; 
    int mid = 0; 
  
    // Iterate till all the elements 
    // are sorted 
    while (mid <= hi) { 
        switch (a[mid]) { 
  
        // If the element is 0 
        case 0: 
            swap(a[lo++], a[mid++]); 
            break; 
  
        // If the element is 1 . 
        case 1: 
            mid++; 
            break; 
  
        // If the element is 2 
        case 2: 
            swap(a[mid], a[hi--]); 
            break; 
        } 
    } 
} 
  
// Function to print array arr[] 
void printArray(int arr[], int arr_size) 
{ 
    // Iterate and print every element 
    for (int i = 0; i < arr_size; i++) 
        cout << arr[i] << " "; 
} 
  
// Driver Code 
int main() 
{ 
    int arr[] = { 0, 1, 1, 0, 1, 2, 1, 2, 0, 0, 0, 1 }; 
    int n = sizeof(arr) / sizeof(arr[0]); 
  
    sort012(arr, n); 
  
    cout << "array after segregation "; 
  
    printArray(arr, n); 
  
    return 0; 
}