How to remove duplicate characters from a String in Scala?

Last Updated : 18 Apr, 2024

In this article, we will learn how to remove duplicate characters from a string in Scala using different approaches. First, we will look through the Brute-Force Approach and then use different standard libraries.

Examples:

Input: String = "hello"
Output: helo

Input: String = "Geeks"
Output: Geks

Naive Approach to remove duplicate characters from a String in Scala

In the brute force approach, we compare each character in the string with every other character to determine if it's a duplicate.

Below is the code in Scala.

Scala

// Program to remove duplicate from string using scala // Creating Object object Gfg {   //Method to removeDuplicates   def removeDuplicates(str: String): String = {     var result = ""     for (char <- str) {       if (!result.contains(char)) {         result += char       }     }     result   }    // Main Method   def main(args: Array[String]): Unit = {     val inputString = "hello"     val outputString = removeDuplicates(inputString)     println(stringWithoutDuplicates)    } }

Output

Explanation:

First we will create a function removeDuplicates
- Inside this function we will took a empty var string.
- We iterate over each character in the input string str.
- For each character, we check if it exists in the result string. If it doesn't, we append it to the result.
- Finally, we return the result string, which contains unique characters.
In main method we will call the removeDuplicate Method and Print the Output.

Time Complexity : O(n²)

Remove duplicate characters from a String in Scala Using Set

This is the another approach using a mutable Set to keep track of duplicate characters.

Below is the code in Scala using set.

Scala

// Program to remove duplicate from string using set  //creating object object Gfg {      //remove duplicate function   def removeDuplicates(str: String): String = {     val set = scala.collection.mutable.Set[Char]()     val result = new StringBuilder     for (char <- str) {       if (!set(char)) {         result += char         contain += char       }     }     result.toString   }    //Main Method   def main(args: Array[String]): Unit = {     val inputString = "hello"     val outputString = removeDuplicates(inputString)     println(outputString)    } }

Output:

Explanation:

First we will define a removeDuplicate Method
- Inside that method we will define a mutable set named set.
- We iterate over each character in the input string str.
- For each character, if it's not already present in the set, we append it to the result string and add it to the set.
- At the end, we convert the result string builder to a regular string and return it.
In main method we will call removeDuplicate Function and Print the Output.

Time Complexity: O(n)
Auxiliary Space: O(n)

Remove duplicate characters from a String in Scala Using foldLeft Method

This is the another method for removing duplicate characters from a String in Scala.

Below is the code in Scala.

Scala

//Creating Object object Gfg {      // defining removeDuplicates Method   def removeDuplicates(str: String): String = {        // Use foldLeft to iterate through each character of the string     str.foldLeft("") { (acc, char) =>      // If the accumulator already contains the character, return the accumulator       if (acc.contains(char)) acc       // Otherwise, append the character to the accumulator       else acc + char     }   }     // Defining Main Method   def main(args: Array[String]): Unit = {     val inputString = "Geeksforgeeks"     val outputString = removeDuplicates(inputString)     println(outputString)   } }

Output:

Explanation:

We define a function removeDuplicates that takes a string str as input and returns a string with duplicate characters removed.
- We use foldLeft to iterate over each character in the input string.
- For each character, we check if it already exists in the accumulator string (acc). If it does, we don't add it to the accumulator. If it doesn't, we append it to the accumulator.
- Finally, we return the accumulator string, which contains unique characters.
We will create Main Method , call the function removeDuplicates and Print that return output.

Remove duplicate characters from a String in Scala Using Distinct Method

The distinct method provides a convenient way to remove duplicate characters from a string in Scala.

Below is the code of remove duplicate characters from a string using string.distinct Method.

Scala

// Creating Object object Gfg {   // defining a removeDuplicate Method   def removeDuplicates(str: String): String = {     // Using string.distinct method     str.distinct   }    //defining main Method   def main(args: Array[String]): Unit = {     val inputString = "Geeksforgeeks"     val outputString = removeDuplicates(inputString)     println(outputString)    } }

Output:

Explanation

The removeDuplicates function simply calls the distinct method on the input string str, which returns a new string with duplicate characters removed.
The main method is the entry point for the program.