Question

Write an application that reads a five-letter word from the user and produces every possible three-letter string that can be derived from the letters of that word. For example, the three-letter words produced from the word "bathe" include "ate," "bat," "bet," "tab," "hat," "the" and "tea."

Short answer

Read the word, generate and filter unique three-letter permutations, then display them.

Step-by-step solution

Accept Input

Ask the user to input a five-letter word. This is needed for creating three-letter combinations. Ensure that the input word contains exactly five letters.

Validate Input

Check if the input word is exactly five letters. If not, prompt the user to enter a valid five-letter word.

Generate Permutations

Use a method to generate all possible permutations of the input word of length three. In Python, you can use the `itertools.permutations` to achieve this.

Filter Unique Permutations

Convert the permutations into a set to eliminate duplicate combinations, as permutations can generate repeated combinations of letters.

Display Results

Print each unique combination of three letters generated from the input word.

Key concepts

String Manipulation

String manipulation is the process of altering, parsing, or analyzing strings within a program. In this exercise, we deal with a string input by the user, specifically a five-letter word. The primary task is to derive all possible three-letter combinations. This requires breaking down the original string and rearranging its characters.

To begin with, each letter of the word is treated as an element in an array. By considering different combinations of these elements taken three at a time, we create new strings. Techniques such as slicing or using libraries like `itertools` in Python assist in generating permutations or combinations of the string.

• Breaking Down Strings: This involves accessing individual characters within the string using indices.
• Permutations and Combinations: These are specific arrangements of the string's characters, often utilized for problems involving anagrams or rearrangements.
• Elimination of Duplicates: After creating permutations, it's important to ensure each combination is unique, often using data structures like sets.

Through these string manipulation techniques, we can efficiently transform a simple input into numerous meaningful combinations.

User Input Validation

User input validation ensures that the data received from a user is appropriate and safe for processing. In the context of this exercise, we are focused on verifying the length of the word provided by the user. The word must be exactly five letters long, no more, no less.

This is crucial for preventing errors that might arise from incorrect inputs. A simple condition check can be employed to determine the string length using the `len()` function in most programming languages. If the input fails this check, the program can gracefully ask the user to re-enter the correct input.

• Length Check: Verifies that the input has exactly five characters.
• Error Messaging: Provides feedback to guide users if they input incorrectly.

By incorporating robust input validation, we enforce the correct use of the application and create a smoother user experience.

Algorithm Design

Algorithm design involves creating a step-by-step method to solve a problem efficiently and effectively. In the case of this exercise, the algorithm must read user input, validate it, generate permutations, filter them, and then present the results.

The process follows a clear sequence:

• Input Acceptance: The algorithm starts by prompting the user for input and ensures compliance with the criteria (five-letter word).
• Validation: An immediate check is conducted to confirm the correct input length before proceeding.
• Permutation Generation: By leveraging methods or libraries, the algorithm generates all possible three-letter combinations.
• Uniqueness Filtering: It removes redundancy by using a set to capture unique permutations only.
• Output Presentation: Finally, it prints out the unique three-letter strings.

Designing an algorithm in this structured way simplifies complex tasks into manageable actions, ensuring the problem is tackled with clarity and efficiency.