【leetcode】【medium】【每日一題】22. Generate Parentheses

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:

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

題目鏈接：https://leetcode-cn.com/problems/generate-parentheses/

 

思路

就是一個遞歸遍歷每種情況的邏輯實現。

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