1122. Relative Sort Array - Explanation

class Solution:
    def relativeSortArray(self, arr1: List[int], arr2: List[int]) -> List[int]:
        res = []

        for num2 in arr2:
            for i, num1 in enumerate(arr1):
                if num1 == num2:
                    res.append(num1)
                    arr1[i] = -1

        arr1.sort()
        for i in range(len(res), len(arr1)):
            res.append(arr1[i])

        return res

class Solution:
    def relativeSortArray(self, arr1: List[int], arr2: List[int]) -> List[int]:
        arr2_set = set(arr2)
        arr1_count = defaultdict(int)
        end = []

        for num in arr1:
            if num not in arr2_set:
                end.append(num)
            arr1_count[num] += 1
        end.sort()

        res = []
        for num in arr2:
            for _ in range(arr1_count[num]):
                res.append(num)
        return res + end

class Solution:
    def relativeSortArray(self, arr1: List[int], arr2: List[int]) -> List[int]:
        count = {}
        for num in arr1:
            count[num] = count.get(num, 0) + 1

        res = []
        for num in arr2:
            res += [num] * count.pop(num)

        for num in sorted(count):
            res += [num] * count[num]

        return res

class Solution:
    def relativeSortArray(self, arr1: List[int], arr2: List[int]) -> List[int]:
        max_val = max(arr1)
        count = [0] * (max_val + 1)

        for num in arr1:
            count[num] += 1

        res = []
        for num in arr2:
            res += [num] * count[num]
            count[num] = 0

        for num in range(len(count)):
            res += [num] * count[num]

        return res

class Solution:
    def relativeSortArray(self, arr1: List[int], arr2: List[int]) -> List[int]:
        index = {num: i for i, num in enumerate(arr2)}
        return sorted(arr1, key=lambda x: (index.get(x, 1000 + x)))