LeetCode-in-All
22. Generate Parentheses
Medium
Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
Example 1:
Input: n = 3
Output: [”((()))”,”(()())”,”(())()”,”()(())”,”()()()”]
Example 2:
Input: n = 1
Output: [”()”]
Constraints:
1 <= n <= 8
Solution
# @param {Integer} n
# @return {String[]}
def generate_parenthesis(n)
res = []
gen(res, '', n, 0, 0)
res
end
def gen(res, str, n, open_num, close_num)
res << str if close_num == n
gen(res, "#{str})", n, open_num, close_num + 1) if close_num < open_num
gen(res, "#{str}(", n, open_num + 1, close_num) if open_num < n
end