Locked
Pass the Dictionary check first
Everything after it builds on dictionaries. Each rep in the check has to be passed without opening the solution. Hints and Basics are fine.
Still to clear · 8 of 8
- Trace: keep the table
- Which line crashes?
- Write: menu from two lists
- Write: total a bill
- Debug: cheapest item
- Write: items under a budget
- Write: who sits where
- Write: apply price changes
Preview · where this ladder is heading
Valid Palindrome
s is a phrase. Only its letters and digits count. Upper and lower case are treated the same. Spaces, punctuation and symbols are ignored completely. Return True if the remaining characters read the same from both ends, otherwise False.
Aim for O(1) extra space. Walk two indexes over the original string instead of building a cleaned copy.
is_palindrome("race a car") → False ("raceacar" backwards is "racaecar") is_palindrome(" ") → True (nothing is left to compare)
ins = "Was it a car or a cat I saw?"outTrue
ins = "race a car"outFalse
ins = " "outTrue
You can read it now. The editor opens when the check is cleared.