S1Q2 · Check for Greeting Prefix¶

⚡ Quick Reference

Function: starts_with_greeting(s: str) -> bool

Core idea: check if the string starts with "Hello " or "Hi " (space included).

def starts_with_greeting(s):
    return s.startswith("Hello ") or s.startswith("Hi ")

Key rules: - The space after the greeting is mandatory - "HelloWorld" is False - Case-sensitive - "hello World" would be False - str.startswith() accepts a tuple to check multiple prefixes at once

Problem Statement¶

Problem

Write a function starts_with_greeting(s) that returns True if s starts with "Hello " or "Hi " (including the trailing space).

Examples:

Input

"Hello World"

Output

True

Input

"Hi There"

Output

True

Input

"HelloWorld"

Output

False

Input

"Greetings Earthling"

Output

False

Tracing all examples¶

Input	`startswith("Hello ")`	`startswith("Hi ")`	Result
`"Hello World"`	✅	❌	`True`
`"Hi There"`	❌	✅	`True`
`"Greetings Earthling"`	❌	❌	`False`
`"HelloWorld"`	❌ (no space)	❌	`False`
`"HiThere"`	❌	❌ (no space)	`False`

Solution approaches¶

Pythonic (startswith with tuple)Explanatory (two checks)Using lambda

def starts_with_greeting(s):
    return s.startswith(("Hello ", "Hi "))

str.startswith() accepts a tuple of prefixes - returns True if the string starts with any of them. The cleanest single-expression solution.

def starts_with_greeting(s):
    return s.startswith("Hello ") or s.startswith("Hi ")

starts_with_greeting = lambda s: s.startswith(("Hello ", "Hi "))

Key takeaways¶

01

The space is part of the prefix

"Hello " includes a trailing space - this ensures "HelloWorld" correctly returns False. Without the space, any string starting with "Hello" would match.

02

startswith() accepts a tuple

s.startswith(("Hello ", "Hi ")) checks both prefixes in one call - cleaner than two separate startswith() calls joined with or. The same trick works with endswith().

03

Case-sensitive by design

startswith() is case-sensitive. "hello World" and "HI there" would both return False. The problem doesn't ask for case-insensitive matching, so no .lower() needed.