Generate Parentheses
给一个数, 返回所有的可能的括号. 求组合, 肯定是dfs, 然后括号肯定是现有左边再有右边. 所以先放左边.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 |
public class Solution { public List<String> generateParenthesis(int n) { List<String> res = new ArrayList<String>(); if(n == 0) return res; dfs(n,n,res,""); return res; } public void dfs(int left, int right, List<String> res, String tmp) { if(left == 0 && right == 0){ res.add(tmp); return; } if(left > 0) { dfs(left - 1, right, res, tmp+'('); } if(right > left) { dfs(left, right - 1, res, tmp+')'); } } } |