Generate Parentheses

題目

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:

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

方法

使用遞歸的思想。

    public void getParen(int left, int right, String str, List<String> list) {if (left == 0 && right == 0) {list.add(str);} else if (left == right) {str += "(";getParen(left - 1, right, str, list);} else {if (left > 0) {String strLeft = str + "(";getParen(left - 1, right, strLeft, list);}if (right > 0) {String strRight = str + ")";getParen(left, right - 1, strRight, list);}}}public List<String> generateParenthesis(int n) {List<String> list = new ArrayList<String>();String str = "";getParen(n, n , str, list);return list;}