LeetCode-Generate Parentheses

题目:

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:

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

采用递归的方式求解

class Solution{
public:
void generate(vector<string> &res,string curr,int m,int n){
if(m==0 && n==0){ //递归终止条件
res.push_back(curr);
return;
}

if(m!=0) generate(res,curr+"(",m-1,n);

if(m<n && n!=0) generate(res,curr+")",m,n-1);
}

vector<string> generateParenthesis(int n){
vector<string> res;
res.clear();

if(n>0){
generate(res,string(),n,n);
}

return ret;
}
};