sort_array_with_0_1_2

def sorting_arr(arr):
    left = 0
    mid = 0
    right = 0
    for i in range(len(arr)):
        if arr[i] == 0:
            left += 1
            arr[left] = 0
        elif arr[i] == 1:
            mid += 1
        else:
            right += 1
    for i in range(len(arr)):
        if i < left:
            arr[i] = 0
        elif left <= i < left+mid:
            arr[i] = 1
        else:
            arr[i] = 2

    print(arr)
sorting_arr([1,2,0,0,2,1,0,2,0,1,2,1])