暴力法、回溯法(卡特兰数)、递归,三个解法一个也没看懂!头痛呀!
今天课程上讲了,好像瞬间懂了
class Solution {
private List<String> list;
public List<String> generateParenthesis(int n) {
list = new ArrayList<>();
_generate(0, 0, n, "");
return list;
}
private void _generate(int left, int right, int n, String s) {
// terminator
if (left == n && right == n) {
list.add(s);
return;
}
// process current logic
// drill down
if (left < n) _generate(left + 1, right, n, s + "(");
if (right < left) _generate(left, right + 1, n, s + ")");
// reverse states
}
}