题目：

题解：

var res []string

func generateParenthesis(n int) []string {
    res = make([]string, 0)
    dfs(n, 0, 0, "")
    return res
}

func dfs(n int, lc int, rc int, path string) {
    if lc == n && rc == n {
        res = append(res, path)
        return 
    } else {
        if lc < n {
            dfs(n, lc + 1, rc, path + "(")
        } 
        if rc < lc {
            dfs(n, lc, rc + 1, path + ")")
        }
    }
    
}