leetcode-grind/1387/main.py

class Solution:

    def __init__(self):
        self.memo = dict()
        self.memo[1] = 0

    def getKth(self, lo, hi, k):
        for i in range(lo, hi + 1):
            self.power(i)

        sort_out = sorted(list(range(lo, hi + 1)), key=lambda x: self.power(x), reverse=False)
        return sort_out[k - 1] # Why is this one-indexed?? SMH

    def power(self, n):
        # first check the memo to ensure we don't do extra work
        # then the array should fill up quickly as we go
        if n in self.memo:
            return self.memo[n]
        elif n % 2 == 0:
            total = 1 + self.power(n//2)
        else:
            total = 1 + self.power(3*n+1)

        self.memo[n] = total
        return total

s = Solution()
print("Expected: 13")
print("Got:", s.getKth(12, 15, 2))