-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathString22.java
More file actions
62 lines (59 loc) · 1.98 KB
/
String22.java
File metadata and controls
62 lines (59 loc) · 1.98 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
package string;
import java.util.ArrayList;
import java.util.List;
/**
* @ProjectName: leetcode
* @Package: string
* @ClassName: String22
* @Author: markey
* @Description:
* 给出 n 代表生成括号的对数，请你写出一个函数，使其能够生成所有可能的并且有效的括号组合。
*
* 例如，给出 n = 3，生成结果为：
*
* [
* "((()))",
* "(()())",
* "(())()",
* "()(())",
* "()()()"
* ]
*
* 来源：力扣（LeetCode）
* 链接：https://leetcode-cn.com/problems/generate-parentheses
* 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
* @Date: 2020/1/5 10:47
* @Version: 1.0
*/
public class String22 {
/**
* Runtime: 2 ms, faster than 20.17% of Java online submissions for Generate Parentheses.
* Memory Usage: 36 MB, less than 100.00% of Java online submissions for Generate Parentheses.
* @param n
* @return
*/
public List<String> generateParenthesis(int n) {
List<StringBuilder> res = generateString(new StringBuilder(""), 0, 0, n);
List<String> result = new ArrayList<>();
for (int i = 0; i < res.size(); i++) {
result.add(res.get(i).toString());
}
return result;
}
private List<StringBuilder> generateString(StringBuilder root, int left, int right, int n) {
List<StringBuilder> res = new ArrayList<>();
if (left >= n) {
StringBuilder rootCopy = new StringBuilder(root);
for (int i = 0; i < n - right; i++) {
rootCopy.append(')');
}
res.add(rootCopy);
} else if (left > right) {
res.addAll(generateString(new StringBuilder(root).append('('), left+1, right, n));
res.addAll(generateString(new StringBuilder(root).append(')'), left, right+1, n));
} else {
res.addAll(generateString(new StringBuilder(root).append('('), left+1, right, n));
}
return res;
}
}