Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
Example 1:
Input: n = 3
Output: ["((()))","(()())","(())()","()(())","()()()"]
Example 2:
Input: n = 1
Output: ["()"]
Constraints:
- 1 <= n <= 8
class Solution {
public List<String> generateParenthesis(int n) {
List<String> list = new ArrayList<>();
backtrack(list,"",0,0,n);
return list;
}
public void backtrack(List<String> list,String str, int open ,int close,int max){
if(str.length()==max*2){
list.add(str);
return;
}
if(open<max){
backtrack(list,str+"(",open+1,close,max);
}
if(close<open){
backtrack(list,str+")",open,close+1,max);
}
}
}