【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:

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

简单DFS
void dfs(int cur,int n,vector<string> &res,string one,int left,int right){
if(cur == 2*n){
res.push_back(one);
return;
}
if(left<n){
dfs(cur+1,n,res,one+"(",left+1,right);
}
if(right<n && left>right){
dfs(cur+1,n,res,one+")",left,right+1);
}
}
vector<string> generateParenthesis(int n) {
vector<string> res;
dfs(0,n,res,"",0,0);
return res;
}