Following example shows how to search duplicate words in a regular expression by using p.matcher() method and m.group() method of regex.Matcher class. Next, use the regular expression to remove consecutive repeated words. Re: most efficient regex to delete duplicate words by maverick (Curate) on Aug 14, 2001 at 00:40 UTC: Here's a non regexp solution. I think I've read about a way to do it using regular expressions instead, but I'm afraid it's not my area of expertise. A new method chars is added to java.lang.String class in java 8. chars returns a stream of characters in the string. Editorial. We count the occurrence of each word in the string. Leaderboard. Url Validation Regex | Regular Expression - Taha match whole word Match or Validate phone number nginx test Blocking site with unblocked games Match html tag Match anything enclosed by square brackets. Invoking distinct method on this stream removes duplicate elements and returns another stream. Given a string, we have to remove all duplicate/repeated words from the string. Examples: Input: str = “Geeks for Geeks A Computer Science portal for Geeks” Output: Geeks for A Computer Science portal Explanation: here ‘Geeks’ and ‘for’ are duplicate so these words are removed from the string The regular expression handles only one duplicate at a time, so we use a loop to go through until we haven't made any changes. In above example, the words highlighted in green are duplicate words. As the problem statement says: you will fail the challenge if you modify anything other than the three locations that the comments direct you to complete Regular Expression Reference. Here is the expected output for some given inputs : Input : topjavatutorial Output : topjavuril Input : hello Output : helo The below program that loops through each character of the String checking if it has already been encountered and … To find the duplicate words from the string, we first split the string into words. HackerRank Problem Java Regex 2 – Duplicate Words Solution September 1, 2017 April 1, 2018 Shrenik 3 Comments In this challenge, we use regular expressions (RegEx) to remove instances of words that are repeated more than once, but retain the first occurrence of any case-insensitive repeated word. I'm assuming that the 'separator' between the words is unimportant. Java Regex 2 - Duplicate Words. If count is greater than 1, it implies that a word has duplicate in the string. And if you need it put back into a string you can rebuild the string from the list. 2) So to get all those strings together first we will join each string in given list of strings. Once we had all the words in the form of a String array, we converted the String array to LinkedHashSet using the asList method of the Arrays class.Since the Set does not allow duplicate elements, duplicate words were not added to the LinkedHashSet. How to match duplicate words in a regular expression? This will also remove duplicates that are not 'next to' each other within the string. Submissions. Solution. Define a string. 4) Join each words are unique to form single string. Ie. In this article, we will discuss how to remove duplicate characters from a String. We check the "haven't made any changes" criteria by using two variables - a "before" and an "after". Discussions. Since our string contained words separated by a space, we first split the string by one or more space characters. Problem. Algorithm. I also found this Regex Matcher Tutorial helpful. 1) Split input sentence separated by space into words. Java Regex 2 - Duplicate Words. 3) Now create a dictionary using Counter method having strings as keys and their frequencies as values. Java solution - passes 100% of test cases. Method 4: Using java 8 streams Java 8 has introduced the concept of streams where an array can be represented as a sequence of elements and operations can be performed on those elements. 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