Sort by Another List's Order

Problem

A shop sorts its stock codes by a preferred order from the marketing team. Given values and a list order of distinct codes, rearrange values so that codes appearing in order come first, grouped and in the same sequence as order, followed by every other code in ascending order. Both lists hold at most 1,000 items, every code in order also appears in values, and each code is between 0 and 1,000.

Examples

Input:  values = [2, 3, 1, 3, 2, 4, 6, 7, 9, 2, 19], order = [2, 1, 4, 3, 9, 6]
Output: [2, 2, 2, 1, 4, 3, 3, 9, 6, 7, 19]
Why:    7 and 19 are not in order, so they go last in ascending order

Input:  values = [28, 6, 22, 8, 44, 17], order = [22, 28, 8, 6]
Output: [22, 28, 8, 6, 17, 44]

Input:  values = [5, 5], order = []
Output: [5, 5]
Why:    edge case, with an empty order the result is a plain ascending sort

Hints

0 / 3

1. Hint 1reveal
2. Hint 2locked
3. Hint 3locked

def relative_sort(values, order, top=1000):
    counts = [0] * (top + 1)
    for v in values:
        counts[v] += 1
    out = []
    for code in order:                 # preferred codes first, grouped
        out += [code] * counts[code]
        counts[code] = 0
    for code in range(top + 1):        # the rest, ascending
        out += [code] * counts[code]
    return out

print(relative_sort([2, 3, 1, 3, 2, 4, 6, 7, 9, 2, 19], [2, 1, 4, 3, 9, 6]))  # -> [2, 2, 2, 1, 4, 3, 3, 9, 6, 7, 19]
print(relative_sort([28, 6, 22, 8, 44, 17], [22, 28, 8, 6]))                 # -> [22, 28, 8, 6, 17, 44]
print(relative_sort([5, 5], []))                                             # -> [5, 5]