All Posts

Determine if a `9 x 9` Sudoku board is valid.

values).

duplicates in-place such that each unique element appears only **once**.

Implement `strStr()`.

You are given an array of `k` linked-lists `lists`, each linked-list is sorted in ascending order.

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent.

Given the head of a linked list, remove the nth node from the end of the list and return its head.

You are given the heads of two sorted linked lists list1 and list2.