C++ Exercises: Sort a given array of 0s, 1s and 2s

C++ Array: Exercise-16 with Solution

Write a C++ program to sort a given array of 0s, 1s and 2s. In the final array put all 0s first, then all 1s and all 2s in last.

Pictorial Presentation:

Sample Solution:

C++ Code :

#include <iostream>
using namespace std;

void swap(int *x, int *y)
{
    int temp = *x;
    *x = *y;
    *y = temp;
}

void sort_012_num(int nums[], int n)
{
    int i = 0;
    int j = n - 1;
    int mid_num = 0;
 
    while (mid_num <= j)
    {
        switch (nums[mid_num])
        {
        case 0:
            swap(&nums[i++], &nums[mid_num++]);
            break;
        case 1:
            mid_num++;
            break;
        case 2:
            swap(&nums[mid_num], &nums[j--]);
            break;
        }
    }
}
 
 
int main()
{
    int nums[] = {0, 1, 2, 2, 1, 1, 0, 0, 1}; 
    int n = sizeof(nums)/sizeof(nums[0]);
   	cout << "Original array: ";
    for (int i=0; i < n; i++) 
    cout << nums[i] <<" ";
    sort_012_num(nums, n);
 
    printf("\nArray elements after rearranging: ");
      for (int i=0; i < n; i++) 
      cout << nums[i] <<" ";
        return 0;
      }

Sample Output:

Original array: 0 1 2 2 1 1 0 0 1 
Array elements after rearranging: 0 0 0 1 1 1 1 2 2    

Flowchart:

C++ Code Editor:

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