22. Generate Parentheses

leetcode.com/problems/generate-parentheses/

Generate Parentheses - LeetCode

class Solution {
    int max;
    List<String> ans = new ArrayList<>();
    public List<String> generateParenthesis(int n) {
        max = n;
        back_track(0, 0, "");
        return ans;
    }
    
    public void back_track(int open, int close, String letter) {
		//종료 조건
		if(letter.length() == max*2) {
			ans.add(letter);
			return;
		}
		if(open < max) {
			back_track(open + 1, close, letter + "(");
		}
		if(close < open) {
			back_track(open, close + 1, letter + ")");
		}
	}
}