Using Regex, we can easily match or search for patterns in a text. Before searching for a pattern, we have to specify one using some well-defined syntax.
In this problem, you are given a pattern. You have to check whether the syntax of the given pattern is valid.
Note: In this problem, a regex is only valid if you can compile it using the Pattern.compile method.
Input Format
The first line of input contains an integer N , denoting the number of test cases. The next N lines contain a string of any printable characters representing the pattern of a regex.
Output Format
For each test case, print Valid if the syntax of the given pattern is correct. Otherwise, print Invalid. Do not print the quotes.
Sample Input
3
([A-Z])(.+)
[AZ[a-z](a-z)
batcatpat(nat
Sample Output
Valid
Invalid
Invalid
Solution
import java.util.Scanner;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
// If a PatternSyntaxException is not thrown by Pattern.compile, the regular expresion is valid
public class Solution {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int testCases = scan.nextInt();
scan.nextLine(); // gets rid of the pesky newline.
while (testCases-- > 0) {
String pattern = scan.nextLine();
try {
Pattern.compile(pattern);
System.out.println("Valid");
} catch (PatternSyntaxException exception) {
System.out.println("Invalid");
}
}
scan.close();
}
}
