Algorithm Notes
Summary: Happy Number — notes not yet curated.
Time: Estimate via loops/recurrences; common classes: O(1), O(log n), O(n), O(n log n), O(n^2)
Space: Count auxiliary structures and recursion depth.
Tip: See the Big-O Guide for how to derive bounds and compare trade-offs.
Big-O Guide
Source
"""
Happy Number
TODO: Add problem description
"""
from src.interview_workbook.leetcode._registry import register_problem
from src.interview_workbook.leetcode._types import Category, Difficulty
class Solution:
def solve(self, *args) -> bool:
"""Determine if a number is a happy number using cycle detection."""
n = args[0]
seen = set()
while n != 1 and n not in seen:
seen.add(n)
n = sum(int(d) ** 2 for d in str(n))
return n == 1
def demo():
"""TODO: Implement demo function."""
pass
register_problem(
id=202,
slug="happy_number",
title="Happy Number",
category=Category.MATH_GEOMETRY,
difficulty=Difficulty.EASY,
tags=["hashmap", "math", "two_pointers"],
url="https://leetcode.com/problems/happy-number/",
notes="",
)