forked from TheAlgorithms/Java
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathLongestValidParentheses.java
More file actions
61 lines (49 loc) · 1.55 KB
/
LongestValidParentheses.java
File metadata and controls
61 lines (49 loc) · 1.55 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
package DynamicProgramming;
import java.util.Scanner;
/**
* Given a string containing just the characters '(' and ')', find the length of
* the longest valid (well-formed) parentheses substring.
*
* @author Libin Yang (https://github.com/yanglbme)
* @since 2018/10/5
*/
public class LongestValidParentheses {
public static int getLongestValidParentheses(String s) {
if (s == null || s.length() < 2) {
return 0;
}
char[] chars = s.toCharArray();
int n = chars.length;
int[] res = new int[n];
res[0] = 0;
res[1] = chars[1] == ')' && chars[0] == '(' ? 2 : 0;
int max = res[1];
for (int i = 2; i < n; ++i) {
if (chars[i] == ')') {
if (chars[i - 1] == '(') {
res[i] = res[i - 2] + 2;
} else {
int index = i - res[i - 1] - 1;
if (index >= 0 && chars[index] == '(') {
// ()(())
res[i] = res[i - 1] + 2 + (index - 1 >= 0 ? res[index - 1] : 0);
}
}
}
max = Math.max(max, res[i]);
}
return max;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while (true) {
String str = sc.nextLine();
if ("quit".equals(str)) {
break;
}
int len = getLongestValidParentheses(str);
System.out.println(len);
}
sc.close();
}
}