Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
For example, given n = 3, a solution set is:
[
"((()))",
"(()())",
"(())()",
"()(())",
"()()()"
]
class Solution(object):
def generateParenthesis(self, n):
"""
:type n: int
:rtype: List[str]
"""
def dfs(left, path, res, n):
if len(path) == 2 * n:
if left == 0:
res.append("".join(path))
return
if left < n:
path.append("(")
dfs(left + 1, path, res, n)
path.pop()
if left > 0:
path.append(")")
dfs(left - 1, path, res, n)
path.pop()
res = []
dfs(0, [], res, n)
return res
