All problems
Strings problems
12 problems: 4 easy, 8 medium and 0 hard. Start at the top; each one assumes the ones above it.
- Not startedEasyCancel out neighbouring pairsStacks and queues, Strings
- Not startedEasyIs it a palindromeTwo pointers, Strings
- Not startedEasyValid anagramSorting, Hash maps, Strings
- Not startedEasyValid parenthesesStacks and queues, Strings
- Not startedMediumArithmetic without bracketsStacks and queues, Strings
- Not startedMediumBest run after k changesSliding window, Strings
- Not startedMediumEvery arrangement of the letters, each one onceBacktracking, Strings
- Not startedMediumEvery way the brackets can balanceBacktracking, Strings
- Not startedMediumGroup anagramsSorting, Hash maps, Strings
- Not startedMediumHow many words start with thisTries, Strings
- Not startedMediumLongest stretch with no repeatsSliding window, Hash maps, Strings
- Not startedMediumThe first letter that has appeared only once, so farStacks and queues, Hash maps, Strings