Given a digit string, return all possible letter combinations that the number could represent.

Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.

Given a set of candidate numbers (candidates) (without duplicates) and a target number (target), find all unique combinations in candidates where the candidate ...

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique s...

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

来了来了，终于来了！上篇文章我们实现了方块的生成和交换，那本篇文章就到了该系列的重头戏，我们一起来实现消消乐的消除算法！

Avoid errors. Readability. Not everyone has the operator table memorized.

意思说 给你一组正数C，然后 给你一个目标数T， 让你从那组C中找到加在一起等于T的那些组合。 比如 给你7 然后 从[2,3,6,7]中可以找到[2,2,3]和[7]两组组合。 想了一下还是用DFS：...

permutations/combinations/combinations_with_replacement

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