Practice · judged on hidden tests
Problems
12 problems, ordered so each topic builds on the last.
- Not startedArithmetic without bracketsStacks and queues, StringsMedium
- Not startedBest run after k changesStrings, Sliding windowMedium
- Not startedCancel out neighbouring pairsStacks and queues, StringsEasy
- Not startedEvery arrangement of the letters, each one onceStrings, BacktrackingMedium
- Not startedEvery way the brackets can balanceStrings, BacktrackingMedium
- Not startedGroup anagramsStrings, Hash maps, SortingMedium
- Not startedHow many words start with thisStrings, TriesMedium
- Not startedIs it a palindromeTwo pointers, StringsEasy
- Not startedLongest stretch with no repeatsStrings, Hash maps, Sliding windowMedium
- Not startedThe first letter that has appeared only once, so farStacks and queues, Strings, Hash mapsMedium
- Not startedValid anagramStrings, Hash maps, SortingEasy
- Not startedValid parenthesesStacks and queues, StringsEasy