22. Generate Parentheses

Problem Statement

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

Solution:

java

import java.util.ArrayList;
import java.util.List;

class Solution {
    public List<String> generateParenthesis(int n) {
        List<String> ans = new ArrayList<>();
        backtrack(ans, "", 0, 0, n);
        return ans;
    }

    private void backtrack(List<String> ans, String str, int open, int close, int n) {
        if (str.length() == n * 2) {
            ans.add(str);
            return;
        }

        if (open < n)
            backtrack(ans, str + "(", open + 1, close, n);

        if (close < open)
            backtrack(ans, str + ")", open, close + 1, n);
    }
}

22. Generate Parentheses #

Problem Statement #

Solution: #

... #

22. Generate Parentheses

Problem Statement

Solution:

...