22. Generate Parentheses 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: [ "((()))", "(()())", "(())()", "()(())", "()()()" ] //mine public class Solution { public List generateParenthesis(int n) { List res = new ArrayList(); if(n<=0) return res; generate("", 0, 0, n, res); return res; } private void generate(String cur, int l, int r, int n, List res) { if(l==n && r==n) { res.add(cur); return; } if(l