Collatz Problem Done

1387/main.py

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+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))

1387/problem.txt

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+The power of an integer x is defined as the number of steps needed to transform x into 1 using the following steps:
+
+    if x is even then x = x / 2
+    if x is odd then x = 3 * x + 1
+
+For example, the power of x = 3 is 7 because 3 needs 7 steps to become 1 (3 --> 10 --> 5 --> 16 --> 8 --> 4 --> 2 --> 1).
+
+Given three integers lo, hi and k. The task is to sort all integers in the interval [lo, hi] by the power value in ascending order, if two or more integers have the same power value sort them by ascending order.
+
+Return the k-th integer in the range [lo, hi] sorted by the power value.
+
+Notice that for any integer x (lo <= x <= hi) it is guaranteed that x will transform into 1 using these steps and that the power of x is will fit in 32 bit signed integer.
+
+ 
+
+Example 1:
+
+Input: lo = 12, hi = 15, k = 2
+Output: 13
+Explanation: The power of 12 is 9 (12 --> 6 --> 3 --> 10 --> 5 --> 16 --> 8 --> 4 --> 2 --> 1)
+The power of 13 is 9
+The power of 14 is 17
+The power of 15 is 17
+The interval sorted by the power value [12,13,14,15]. For k = 2 answer is the second element which is 13.
+Notice that 12 and 13 have the same power value and we sorted them in ascending order. Same for 14 and 15.
+
+Example 2:
+
+Input: lo = 1, hi = 1, k = 1
+Output: 1
+
+Example 3:
+
+Input: lo = 7, hi = 11, k = 4
+Output: 7
+Explanation: The power array corresponding to the interval [7, 8, 9, 10, 11] is [16, 3, 19, 6, 14].
+The interval sorted by power is [8, 10, 11, 7, 9].
+The fourth number in the sorted array is 7.
+
+Example 4:
+
+Input: lo = 10, hi = 20, k = 5
+Output: 13
+
+Example 5:
+
+Input: lo = 1, hi = 1000, k = 777
+Output: 570
+
+ 
+
+Constraints:
+
+    1 <= lo <= hi <= 1000
+    1 <= k <= hi - lo + 1
+

1387/run.sh

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+#!/bin/bash
+
+python3 main.py