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.
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+')');
}
}
}