* duplicate characters from String in place to boost performance. * simplifies the solution and second one will remove the * show you how use of a suitable data structure like HashSet or HashMap
* We'll see two solutions for this problem, first one will * Java Program to remove duplicate characters from String. Our solution is based upon this knowledge, but it becomes more elegant by using StringBuffer for creating output String.add() method of Set return false if the element already exists in Set and by using that we can create a StringBuilder with only unique characters.Ĭonverting a StringBuilder to String is a trivial task in Java but if you are not familiar with essential Java API then I suggest you join The Complete Java Masterclass by Tim Buchalaka on Udemy, one of the most comprehensive and up-to-date courses to learn Java online. The Set data structure doesn't allow duplicate characters, so if you convert your String to a character array, loop over it, add each element into HashSet, you will end up with a Set without duplicate characters.
By the way, if you are using Java, then you have a better choice, HashSet, which is a combination of set and hash table data structure. If you take a hash table, we will get O(1) for insert and find operation. To remove duplicate characters from String, we need a data structure where insertion and search would be super fast. The next solution is an exquisite one, and it demonstrates how you can simplify your algorithm by choosing an appropriate data structure. Solution 2 - Using a Data Structure like Set If you want to learn more about stable sorting algorithms, I suggest you take a look at the Algorithms and Data Structures - Part 1 and 2 courses on Pluralsight. So if the interviewer asks you to keep elements in their original order, this solution will fall short, but for the practical purpose, this would work because you are dealing with duplicate characters.
Though this solution has a drawback, i t doesn't preserve the original order of the element. All you need to do is iterate over sorted character array, compare the current element with the previous element, and discard it if they are the same.Īt the end of the iteration, your array only contains unique characters. If we get the character array from String and then sort it using MergeSort or QuickSort in O(N log N) time, we can easily remove duplicates in linear time, because they will be clubbed together. This means you can use all the ways we have used previously. If you pay a little bit of attention, then you can easily find that removing duplicate characters from String is nothing but removing duplicates from an array. Solution 1 - Sorting and Removing Duplicates Now that, you are familiar with both problems and some approaches to remove duplicate characters from given String in Java let's deep dive into solutions to this classic coding problem and analyze their time and space complexity.
#Delete duplicacy in string in java how to
How to remove repeated characters from a given String in Java The third approach would be the brute force way of taking one string at a time and then removing all other occurrences of that string, rearranging the array, and then starting with the next element. This would tradeoff space for time, as the space complexity of this solution would be O(n). Second, use an auxiliary data structure like Set to keep track of characters already seen and then recreate String from Set. There are three main ways to remove duplicate characters from String in Java First to sort the character array of string and then remove duplicate characters in linear time. If you know how to solve that problem, you should be able to solve this one as well. This problem is very similar to removing duplicate elements from an array which we have discussed in the past here after all String is a character array in Java. How do you remove duplicate or repeated characters from String in Java is one of the frequently asked string-based coding problems from Interviews. Never mind, today, you are going to learn about another popular coding problem. The last one I discussed was about finding the Nth Fibonacci number, one of the popular dynamic programming problems.
Hello all, how are you doing? It's been a long since I have shared a coding problem from the interview.
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