문제 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 { if(n * 2 === s.length) { result.push(s) return; } if(l < n) dfs(s + '(', l + 1, r); if(r < l) dfs(s + ')', l, r + 1); } dfs('', 0, 0) return result; }