LeetCode题解：Generate Parentheses

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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：

左右括号总数相同，且在填充时左括号的个数始终要大于等于右括号的个数。据此递归生成所有的括号对。

题解：

class Solution {public:    vector<string> result;        void generate_string(const string str, int lpnum, int rpnum)    {        if (lpnum == 0 && rpnum == 0)        {            result.push_back(str);            return;        }                if (lpnum > 0)            generate_string(str + '(', lpnum - 1, rpnum);                if (rpnum > lpnum)            generate_string(str + ')', lpnum, rpnum - 1);    }        vector<string> generateParenthesis(int n) {        result.clear();                generate_string("", n, n);                return result;    }};