leetcode Generate Parentheses 难度系数3 3.10

Question:

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:

"((()))", "(()())", "(())()", "()(())", "()()()"

public class Solution {
	public ArrayList<String> generateParenthesis(int n) {
		ArrayList<String> results = new ArrayList<String>();
		if (n == 0) {
			results.add("");
			return results;
		}
		if (n == 1) {
			results.clear();
			results.add("()");
			return results;
		}
		results.clear();
		if (n > 1) {
			subGenerate(n, "", 0, 0, results);
		}
		return results;
	}

	private void subGenerate(int n, String result, int left, int right,
			ArrayList<String> results) {
		if (left==n) {
			while(n-right>0){
				result+=")";
				right++;
			}
			results.add(result);
			return;
		}
		subGenerate(n, result+"(", left+1, right, results);
		if (left>right) {
			subGenerate(n, result+")", left, right+1, results);
		}
	}
}

leetcode Generate Parentheses 难度系数3 3.10

原文：http://blog.csdn.net/yiding_he/article/details/18893387