22. Generate Parentheses.md

22. Generate Parentheses

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
给定n对括号，写一个函数来生成形式良好的括号的所有组合

For example, given n = 3, a solution set is:

[
  "((()))",
  "(()())",
  "(())()",
  "()(())",
  "()()()"
]

Solution