LeetCode

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:

[  "((()))",  "(()())",  "(())()",  "()(())",  "()()()"]

给出一个数字n，返回n对括号的所有可能组合。

dfs一下

class Solution {public:    vector<string> generateParenthesis(int n) {        vector<string> ans;        solve(ans, "", n, n);        return ans;    }        void solve(vector<string>& ans, string s, int n, int m) {        if (n < 0 || m < 0 || m < n) return;        if (n == 0 && m == 0) {            ans.push_back(s);            return;        }                solve(ans, s + "(", n-1, m);        solve(ans, s + ")", n, m-1);    }};