20260719

• LeetCode
  • 231. Power of Two
  • 342. Power of Four
    • modulo
  • 326. Power of Three
  • 26. Remove Duplicates from Sorted Array
• squats, push ups, 2k run, 16000 steps in total
• planed with Chrome extension (overriding GitHub CSS)
  • created the color palette with eye-saver mode enabled. I was surprised when I turned off the eye-saver mode finding out it looks very different.

20260718

• 反ミーム部門は存在しない
• LeetCode
  • 26. Remove Duplicates from Sorted Array (code review)
• squats, 2k run, 10000 steps in total
• diet log in ChatGPT

20260717

• work (hecking hard - so many pull requests)
• git push --force-with-lease
• diet log in ChatGPT
• squats, 6k jog, 18000 steps in total

20260716

• started a thread on a diet
• work (hard)
• LeetCode
  • 231. Power of Two
  • 342. Power of Four
  • 326. Power of Three
    • I could find the pattern after ChatGPT gave me a subtle hint, but estimating the specific number
    • Invert + add 1
    • the most significant bit is the sign bit in the two’s complement representation.
• squats, push ups, 1 hour walk

class Solution:
    def isPowerOfThree(self, n: int) -> bool:
        if n <= 0:
            return False

        return 3 ** 19 % n == 0

20260715

• work (hard)
• sushida
• checked apple/container

  • container is a tool that you can use to create and run Linux containers as lightweight virtual machines on your Mac. It’s written in Swift, and optimized for Apple silicon.

• LeetCode
  • 231. Power of Two
  • 342. Power of Four
  • 326. Power of Three
• squats, push ups, 4k jog

20260714

• LeetCode
  • 342. Power of Four
    • loop, bitmask, modulo
  • 231. Power of Two
    • n & (n - 1) == 0, loop
• work (very hard)
• squats, push ups, 4k jog

class Solution:
    def isPowerOfFour(self, n: int) -> bool:
        # 4 ≡ 1 (mod 3)
        # 4^k ≡ 1^k ≡ 1 (mod 3)

        if n <= 0:
            return False

        if n & (n - 1) != 0:
            return False

        return n % 3 == 1

20260713

• LeetCode
  • 342. Power of Four
    • practiced the loop-based solution three times
    • practiced the bitmask solution three times
• squats, push ups, 20 minutes indoor jog
• work (Why am I working so hard?)

class Solution:
    def isPowerOfFour(self, n: int) -> bool:
        # 1 -> 1
        # 4 -> 100
        # 16 -> 10000

        if n <= 0:
            return False

        if n & (n - 1) != 0:
            return False

        EVEN_BIT_MASK = 0x55555555
        return n & EVEN_BIT_MASK != 0

20260712

• Computer Organization and Design
• work (hard)
• LeetCode
  • 342. Power of Four
    • I missed to ues 2^10 = 1024 =~ 10 ^ 3
    • n & (n - 1) == 0
    • tomorrow, I’ll explore the math trick approach
• squats, 4k jog

CPU Core
   │
Registers    (~1 KB, fastest)
   │
L1 Cache     (~32–64 KB)
   │
L2 Cache     (~256 KB–2 MB)
   │
L3 Cache     (~8–64 MB)
   │
RAM          (GBs)
   │
SSD / HDD    (TBs)

The number of cache levels in a CPU is a design choice that balances speed, capacity, power, and cost.

class Solution:
    def isPowerOfFour(self, n: int) -> bool:
        return (
            n > 0  # 4 ^ x cannot be negative
            and n & (n - 1) == 0  # exactly one bit is set
            and n & 0x55555555 == n  # 1 bit at even position - 4 ^ x
            # and (n & 0x55555555) != 0  # alternative
        )

20260711

• work
  • update tickets
  • code review
  • publish changes
• LeetCode
  • 70. Climbing Stairs
    • recursion, dp, dp with a fixed memory
  • 310. Minimum Height Trees
• 7/11 free slurpee
• squats

# I know this solution does not pass the test cases
# This is just for my reference
import collections


class Solution:
    def findMinHeightTrees(self, n: int, edges: list[list[int]]) -> list[int]:
        node_to_neighbors = collections.defaultdict(list)
        for node1, node2 in edges:
            node_to_neighbors[node1].append(node2)
            node_to_neighbors[node2].append(node1)

        def get_height(node: int, parent: int) -> int:
            return max(
                (
                    get_height(neighbor, node)
                    for neighbor in node_to_neighbors[node]
                    if neighbor != parent
                ),
                default=0
            ) + 1

        min_height = float("inf")
        min_roots = []
        for node in range(n):
            height = get_height(node, None)
            if height > min_height:
                continue
            elif height < min_height:
                min_height = height
                min_roots = [node]
            else:  # height == min_height
                min_roots.append(node)

        return min_roots

20260710

• work
• squats, chest press, lat pull down
• OWASP Top 10:2025
• LeetCode 200. Number of Islands

20250709

• push ups, squats
• work
• I wore a kurta to the office.

20260708

• Darkest Dungeon
• Hunter x Hunter
• rest

20260707

• work (some chores)
• submitted reimbersement requests

20250706

• rest
• drawing

20260621-20260705

• business trip to India

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