22. Generate Parentheses
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:
[
“((()))”,
“(()())”,
“(())()”,
“()(())”,
“()()()”
]
题目的意思是给你几组括号,然后求这括号的任意组合,开和闭必须对应
这道题不会做,看了一个大神的思路。用递归做的,开始确实比较难看懂,不过通过一步一步调试
也算懂了
public List<String> generateParenthesis(int n) {
List<String> list = new ArrayList<String>();
backtrack(list, "", 0, 0, n);
return list;
}
public void backtrack(List<String> list, String str, int open, int close, int max){
if(str.length() == max*2){
list.add(str);
return;
}
if(open < max)backtrack(list, str+"(", open+1, close, max);
if(close < open)backtrack(list, str+")", open, close+1, max);
}
不太好讲,一步一步调试就懂了