Sort 0s, 1s, and 2s Problem Statement

You are provided with an integer array/list ARR of size 'N' which consists solely of 0s, 1s, and 2s. Your task is to write a solution to sort this array/list.

Input:

The first line contains an integer 'T' which denotes the number of test cases. For each test case, the first line contains an integer 'N' denoting the size of the array/list. The second line contains 'N' space-separated integers representing the elements of the array/list.

Output:

For each test case, output the sorted array/list ARR as space-separated integers. Each test case should be printed on a new line.

Example:

Input: 2 5 0 2 1 2 0 3 2 1 0

Output:

0 0 1 2 2 0 1 2

Constraints:

1

Question

Sort 0s, 1s, and 2s Problem Statement

You are provided with an integer array/list ARR of size 'N' which consists solely of 0s, 1s, and 2s. Your task is to write a solution to sort this array/list.

Input:

The first line contains an integer 'T' which denotes the number of test cases. For each test case, the first line contains an integer 'N' denoting the size of the array/list. The second line contains 'N' space-separated integers representing the elements of the array/list.

Output:

For each test case, output the sorted array/list ARR as space-separated integers. Each test case should be printed on a new line.

Example:

Input: 
2
5
0 2 1 2 0
3
2 1 0

Output:

0 0 1 2 2
0 1 2

Constraints:

1 <= T <= 10
1 <= N <= 5 * 10⁵
0 <= ARR[i] <= 2

Note:

Try to implement the solution with a 'Single Scan' approach, meaning you should attempt to sort the array by iterating over it just once. You are required to modify the given array/list directly.

Accepted Answer

Sort an array of 0s, 1s, and 2s in linear time with a single scan approach.

Use three pointers to keep track of the positions of 0s, 1s, and 2s in the array.
Iterate through the array once and swap elements based on their values and the pointers.
After the single scan, the array will be sorted in place with 0s, 1s, and 2s in order.

Accepted Answer

vector<int> solve(int n, vector<int> arr){
    int low = 0;
    int high = n-1;
    int mid = 0;

    while(mid <= high){
        switch(arr[mid]){
        case 0:
            swap(arr[mid++], arr[low++]);
            break;
    
        case 1:
            mid++;
            break;

        case 2:
            swap(arr[mid++], arr[high--]);
            break;
        }
    }
    
return arr;
}

Sort 0s, 1s, and 2s Problem Statement

Input:

Output:

Example:

Output:

Constraints:

Note:

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