leetcode 022 Generate Parentheses

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题目

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:

"((()))", "(()())", "(())()", "()(())", "()()()"

思路：

利用递归求解，递归这玩意不好解释，建议调试几次，追踪代码执行过程，用机器的方式去思考。

代码：

private List<String> list;public List<String> generateParenthesis(int n){    String s = "";    list = new ArrayList<>();    generate(n, n, s);    return list;}void generate(int left, int right, String s){    if(left != 0)    {        generate(left - 1, right, s + "(");        if(left != right)        {            generate(left, right - 1, s + ")");        }    } else    {        if(right != 0)        {            int tmp = right;            StringBuilder builder = new StringBuilder(s);            while(tmp-- > 0)                builder.append(')');            list.add(builder.toString());        }    }}

结果细节（图）：

0 0