Java: Count the number of triples (characters appearing three times in a row) in a given string

Last update on May 21 2025 12:48:43 (UTC/GMT +8 hours)

86. Count Triples in String

Write a Java program to count the number of triples (characters appearing three times in a row) in a given string.

Sample Solution:

Java Code:

// Define a class named Main
public class Main {
  
  // Method to count the number of triples in the given string
  public int noOfTriples(String stng) {
    int l = stng.length(); // Get the length of the given string
    int ctr = 0; // Initialize a counter for triples
  
    // Loop through the string to check for triples
    for (int i = 0; i < l - 2; i++) {
      char tmp = stng.charAt(i); // Get the character at index 'i'

      // Check if the character at index 'i' is the same as the next two characters
      if (tmp == stng.charAt(i + 1) && tmp == stng.charAt(i + 2)) {
        ctr++; // Increment the counter if a triple is found
      }
    }
    return ctr; // Return the total count of triples
  }

  // Main method to execute the program
  public static void main(String[] args) {
    Main m = new Main(); // Create an instance of the Main class

    String str1 = "welllcommmmeee"; // Given input string

    // Display the given string and the number of triples in it
    System.out.println("The given string is: " + str1);
    System.out.println("The number of triples in the string is: " + m.noOfTriples(str1));
  }
}

Sample Output:

The given string is: welllcommmmeee
The number of triples in the string is: 4

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to count groups of three identical consecutive characters in a string.
• Write a Java program to detect and tally all occurrences of triple repeated characters in the input string.
• Write a Java program to iterate over a string and count every instance where the same character appears three times in succession.
• Write a Java program to compute the number of triplets of identical characters using pattern matching.

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