How To Take Duplicate Characters From String Inward Java
This week's coding exercise is to remove duplicate characters from String inwards Java. For example, if given String is "aaaaaa" together with so output should locomote "a", because residual of the "a" are duplicates. Similarly, if the input is "abcd" together with so output should too locomote "abcd" because in that place is no duplicate graphic symbol inwards this String. By the way, you lot tin non purpose whatever third-party library or Java API method to solve this problem, you lot demand to develop your ain logic or algorithm together with and so write code to implement that algorithm. This is ane of the interesting problems from Java coding interviews together with you lot tin purpose this programme to weed out Java programmers who cannot write code. This employment is much amend than Fizzbuzz because it requires to a greater extent than logic together with coding than solving Fizzbuzz.
In this article, I'll portion 2 ways to withdraw duplicate characters from String together with volition speak over the pros together with cons, the fourth dimension complexity of each solution. Sometimes, a pick is restricted past times putting additional constraint set past times the interviewer, that's why it's amend to know multiple ways to solve a problem. This non alone helps inwards agreement the employment amend precisely too on comparative analysis.
Btw, This is a real pop coding based query on tech companies labor interviews together with you lot volition this employment inwards all expert coding interview questions books e.g. Cracking the Coding Interview, which contains to a greater extent than than189 code-based problems from diverse interviews.
The fourth dimension Complexity of this solution is O(n^2), excluded to uniqueString() method, which creates a String from the graphic symbol array. This method volition locomote fifty-fifty if input String contains to a greater extent than than ane duplicate characters.
This algorithm is too an event of beast forcefulness algorithm to solve a programming problem. To larn to a greater extent than near unlike types of algorithms inwards the programming basis e.g. greedy algorithm, you lot should cheque Introduction to Algorithm past times Thomas Cormen, ane of the best books to larn estimator algorithms.
This Algorithm uses an additional retention of constant size. It creates a boolean array of length 256 to adjust all ASCII characters. Initially, all array elements are false. This array is used every bit a Set to cheque if an ASCII graphic symbol is seen already or not. You iterate over graphic symbol array together with grade all characters which are seen past times storing truthful inwards the corresponding index of ASCII array.
For example, if input String is "abcda" together with so ASCII['a'] = true agency at index 65 truthful is stored, adjacent fourth dimension when you lot abide by this graphic symbol 'a', you lot know that this graphic symbol has appeared earlier because of truthful chemical cistron thus it's duplicate, so you lot shop hither ZERO or NUL. Later you lot withdraw all those characters together with do a unique String every bit output. See Unicode demystified to larn to a greater extent than near encoding system inwards the estimator world.
That's all near how to withdraw duplicate characters from given String inwards Java. You tin purpose this logic to withdraw duplicate values from the array inwards Java every bit well. If you lot demand to a greater extent than practice, you lot tin cheque out t the Cracking the Coding Interview book. It contains to a greater extent than than 190 problems together with their solutions from diverse tech companies programming labor interviews.
Further Learning
The Coding Interview Bootcamp: Algorithms + Data Structures
Data Structures together with Algorithms: Deep Dive Using Java
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In this article, I'll portion 2 ways to withdraw duplicate characters from String together with volition speak over the pros together with cons, the fourth dimension complexity of each solution. Sometimes, a pick is restricted past times putting additional constraint set past times the interviewer, that's why it's amend to know multiple ways to solve a problem. This non alone helps inwards agreement the employment amend precisely too on comparative analysis.
Btw, This is a real pop coding based query on tech companies labor interviews together with you lot volition this employment inwards all expert coding interview questions books e.g. Cracking the Coding Interview, which contains to a greater extent than than189 code-based problems from diverse interviews.
Solution 1 - Replacing duplicate amongst NUL character
Our offset solution is coded inwards the method removeDuplicates(String word), it takes a String together with returns around other String without duplicates. This algorithm goes through each graphic symbol of String to cheque if it's a duplicate of an already flora character. It skips the duplicate graphic symbol past times inserting 0, which is afterward used to filter those characters together with update the non-duplicate characters.The fourth dimension Complexity of this solution is O(n^2), excluded to uniqueString() method, which creates a String from the graphic symbol array. This method volition locomote fifty-fifty if input String contains to a greater extent than than ane duplicate characters.
This algorithm is too an event of beast forcefulness algorithm to solve a programming problem. To larn to a greater extent than near unlike types of algorithms inwards the programming basis e.g. greedy algorithm, you lot should cheque Introduction to Algorithm past times Thomas Cormen, ane of the best books to larn estimator algorithms.
Solution 2 - Using ASCII table
Our mo solution is coded inwards removeDuplicatesFromString(String input) method. This solution assumes that given input String alone contains ASCII characters. You should inquire this query to your Interviewer, if he says ASCII together with so this solution is Ok.This Algorithm uses an additional retention of constant size. It creates a boolean array of length 256 to adjust all ASCII characters. Initially, all array elements are false. This array is used every bit a Set to cheque if an ASCII graphic symbol is seen already or not. You iterate over graphic symbol array together with grade all characters which are seen past times storing truthful inwards the corresponding index of ASCII array.
For example, if input String is "abcda" together with so ASCII['a'] = true agency at index 65 truthful is stored, adjacent fourth dimension when you lot abide by this graphic symbol 'a', you lot know that this graphic symbol has appeared earlier because of truthful chemical cistron thus it's duplicate, so you lot shop hither ZERO or NUL. Later you lot withdraw all those characters together with do a unique String every bit output. See Unicode demystified to larn to a greater extent than near encoding system inwards the estimator world.
Java Solution - Remove duplicate characters from given String
Here is my solution for the employment of removing repeated or duplicate characters from given String inwards Java programming language. If you lot empathise the logic you lot tin write this solution inwards whatever programming linguistic communication e.g. C, C++, C#, Python or JavaScript./** * Java Program to withdraw duplicate characters from String. * * @author Javin Paul */ public class RemoveDuplicateCharacters{ public static void main(String args[]) { System.out.println("Call removeDuplicates(String word) method ...."); String[] testdata = {"aabscs", "abcd", "aaaa", null, "", "aaabbb", "abababa"}; for (String input : testdata) { System.out.printf("Input : %s Output: %s %n", input, removeDuplicates(input)); } System.out.println("Calling removeDuplicatesFromString(String str)."); for (String input : testdata) { System.out.printf("Input : %s Output: %s %n", input, removeDuplicatesFromString(input)); } } /* * This algorithm goes through each graphic symbol of String to cheque if its * a duplicate of already flora character. It skip the duplicate * graphic symbol past times inserting 0, which is afterward used to filter those * characters together with update the non-duplicate character. * Time Complexity of this solution is O(n^2), excluded to * UniqueString() method, which creates String from graphic symbol array. * This method volition locomote fifty-fifty if String contains to a greater extent than than ane duplicate * character. */ public static String removeDuplicates(String word) { if (word == null || word.length() < 2) { return word; } int pos = 1; // possible seat of duplicate character char[] characters = word.toCharArray(); for (int i = 1; i < word.length(); i++) { int j; for (j = 0; j < pos; ++j) { if (characters[i] == characters[j]) { break; } } if (j == pos) { characters[pos] = characters[i]; ++pos; } else { characters[pos] = 0; ++pos; } } return toUniqueString(characters); } /* * This solution assumes that given input String alone contains * ASCII characters. You should inquire this query to your Interviewer, * if he says ASCII together with so this solution is Ok. This Algorithm * uses additional retention of constant size. */ public static String removeDuplicatesFromString(String input) { if (input == null || input.length() < 2) { return input; } boolean[] ASCII = new boolean[256]; char[] characters = input.toCharArray(); ASCII[input.charAt(0)] = true; int dupIndex = 1; for (int i = 1; i < input.length(); i++) { if (!ASCII[input.charAt(i)]) { characters[dupIndex] = characters[i]; ++dupIndex; ASCII[characters[i]] = true; } else { characters[dupIndex] = 0; ++dupIndex; } } return toUniqueString(characters); } /* * Utility method to convert Character array to String, omitting * NUL character, ASCII value 0. */ public static String toUniqueString(char[] letters) { StringBuilder sb = new StringBuilder(letters.length); for (char c : letters) { if (c != 0) { sb.append(c); } } return sb.toString(); } } Output Call removeDuplicates(String word) method .... Input : aabscs Output: absc Input : abcd Output: abcd Input : aaaa Output: a Input : null Output: null Input : Output: Input : aaabbb Output: ab Input : abababa Output: ab Calling removeDuplicatesFromString(String str) method .... Input : aabscs Output: absc Input : abcd Output: abcd Input : aaaa Output: a Input : null Output: null Input : Output: Input : aaabbb Output: ab Input : abababa Output: ab
That's all near how to withdraw duplicate characters from given String inwards Java. You tin purpose this logic to withdraw duplicate values from the array inwards Java every bit well. If you lot demand to a greater extent than practice, you lot tin cheque out t the Cracking the Coding Interview book. It contains to a greater extent than than 190 problems together with their solutions from diverse tech companies programming labor interviews.
Further Learning
The Coding Interview Bootcamp: Algorithms + Data Structures
Data Structures together with Algorithms: Deep Dive Using Java
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