Leetcode 22. Generate Parentheses

https://leetcode.com/problems/generate-parentheses/

#include<string>
using namespace std;
class Solution {
public:
    vector<int> sta;
    vector<string> ans;
    void gene_next(int n,string s,int sta){
        if(n==0){
            ans.push_back(s+string(sta,')'));
            return;
        }
        if(sta==0){
            gene_next(n-1,s+'(',1);
            return;
        }
        gene_next(n-1,s+'(',sta+1);
        gene_next(n,s+')',sta-1);
        return;
        
    }
    vector<string> generateParenthesis(int n) {
        ans.clear();
        if(n==0) return ans;
        string s="";
        int sta=0;
        gene_next(n,s,sta);
        return ans;
    }
};

python版本

class Solution:
    def generateParenthesis(self, n: int) -> List[str]:
        def next_letter(num,diff,tmp):
            if diff==0 and num==0:
                ans.append(''.join(tmp))
            if diff>0:
                tmp.append(')')
                next_letter(num,diff-1,tmp)
                tmp.pop()
            if num>0:
                tmp.append('(')
                next_letter(num-1,diff+1,tmp)
                tmp.pop()
            return
        ans=[]
        next_letter(n,0,[])
        return ans