thảo luận Leetcode contest, đường tới Guardian

class Solution:
    def findPermutation(self, nums: List[int]) -> List[int]:
        n = len(nums)
        nexts = [[float('inf')] * n for _ in range(1 << n)]
        
        @cache
        def dp(mask, first):
            nonlocal nexts
            if mask == (1 << first):
                return abs(first - nums[0])
            
            min_dp = float('inf')
            for after_first in range(n):
                if after_first == first or ((1 << after_first) & mask) == 0:
                    continue
                
                next_mask = mask - (1 << first)
                curr_dp = abs(first - nums[after_first]) + dp(next_mask, after_first)
                
                if curr_dp < min_dp:
                    min_dp = curr_dp
                    nexts[mask][first] = after_first
            
            return min_dp
        
        res = []
        curr_mask = (1 << n) -1
        curr_first = 0
        dp(curr_mask, curr_first)

        while curr_mask:
            res.append(curr_first)
            next_mask = curr_mask - (1 << curr_first)
            next_first = nexts[curr_mask][curr_first]
            curr_mask, curr_first = next_mask, next_first

        return res