LeetCode题解(1387)：将整数按权重排序(Python)

题目：原题链接（中等）

标签：动态规划、图、排序

解法一：

class Solution:
    def getKth(self, lo: int, hi: int, k: int) -> int:
        dp = {1: 0}

        def dfs(x):
            if x not in dp:
                if x % 2 == 1:
                    dp[x] = dfs(x * 3 + 1) + 1
                else:
                    dp[x] = dfs(x // 2) + 1
            return dp[x]

        lst = []
        for i in range(lo, hi + 1):
            v = dfs(i)
            lst.append((v, i))

        lst.sort()

        return lst[k - 1][1]

解法二：

DP = {1: 0}


class Solution:
    def getKth(self, lo: int, hi: int, k: int) -> int:

        def dfs(x):
            if x not in DP:
                if x % 2 == 1:
                    DP[x] = dfs(x * 3 + 1) + 1
                else:
                    DP[x] = dfs(x // 2) + 1
            return DP[x]

        lst = []
        for i in range(lo, hi + 1):
            v = dfs(i)
            lst.append((v, i))

        lst.sort()

        return lst[k - 1][1]

标签：Python,题解,dfs,int,lst,DP,lo,1387,dp
来源： https://blog.csdn.net/Changxing_J/article/details/112862937