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Text Editor with Undo/Redo Functionality

Certification: Intermediate Level Accuracy: 0% Submissions: 1 Points: 15

Design a text editor with the following operations:

Example 1
    

  • Input: ["TextEditor", "append", "append", "getText", "delete", "getText", "undo", "getText", "redo", "getText"]
[[], ["Hello"], [" World"], [], [5], [], [], [], [], []]
    • 

  • Output: [null, null, null, "Hello World", null, "Hello", null, "Hello World", null, "Hello"]
    • 

  • Explanation: 
      

    • Step 1: TextEditor textEditor = new TextEditor() // Initialize with empty text
      • 

    • Step 2: textEditor.append("Hello") // Text = "Hello"
      • 

    • Step 3: textEditor.append(" World") // Text = "Hello World"
      • 

    • Step 4: textEditor.getText() // Return "Hello World"
      • 

    • Step 5: textEditor.delete(5) // Delete the last 5 characters: " World". Text = "Hello"
      • 

    • Step 6: textEditor.getText() // Return "Hello"
      • 

    • Step 7: textEditor.undo() // Undo the delete operation. Text = "Hello World"
      • 

    • Step 8: textEditor.getText() // Return "Hello World"
      • 

    • Step 9: textEditor.redo() // Redo the delete operation. Text = "Hello"
      • 

    • Step 10: textEditor.getText() // Return "Hello"
      • 

    

    •
Example 2
    

  • Input: ["TextEditor", "append", "select", "copy", "append", "select", "paste", "getText", "undo", "getText"]
[[], ["Programming"], [0, 3], [], [" is fun"], [14, 16], [], [], [], []]
    • 

  • Output: [null, null, null, null, null, null, null, "Programming is Prog", null, "Programming is fun"]
    • 

  • Explanation: 
      

    • Step 1: TextEditor textEditor = new TextEditor() // Initialize with empty text
      • 

    • Step 2: textEditor.append("Programming") // Text = "Programming"
      • 

    • Step 3: textEditor.select(0, 3) // Select "Prog"
      • 

    • Step 4: textEditor.copy() // Clipboard = "Prog"
      • 

    • Step 5: textEditor.append(" is fun") // Text = "Programming is fun"
      • 

    • Step 6: textEditor.select(14, 16) // Select "fun"
      • 

    • Step 7: textEditor.paste() // Replace "fun" with "Prog". Text = "Programming is Prog"
      • 

    • Step 8: textEditor.getText() // Return "Programming is Prog"
      • 

    • Step 9: textEditor.undo() // Undo the paste operation. Text = "Programming is fun"
      • 

    • Step 10: textEditor.getText() // Return "Programming is fun"
      • 

    

    •
Constraints
    

  • 1 ≤ text.length ≤ 10^4
    • 

  • 0 ≤ k ≤ 10^4
    • 

  • 0 ≤ start ≤ end < current text length
    • 

  • At most 10^4 calls will be made to the functions.
    • 

  • The sum of the lengths of all appended strings will not exceed 10^5.
    • 

  • Time Complexity: All operations should be O(n) or better.
    • 

  • Space Complexity: O(n) for storing the text and operation history.
    •
StackData StructureTech MahindraLTIMindtree
Editorial

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Hint
Solution

Solution Hints

    
    
  • Use a data structure to store the text (StringBuilder or equivalent).
    • 
    
  • Implement a stack-based system to keep track of operations for undo/redo functionality.
    • 
    
  • Create an Operation class to represent different types of operations and their parameters.
    • 
    
  • Keep track of the current selection for copy/paste operations.
    • 
    
  • Design a state-based system to track changes and allow for undo/redo.
    •

Steps to solve by this approach:

 Step 1: Create a class to represent different types of operations (append, delete, paste) with their parameters

 Step 2: Implement stacks to track operations for undo and redo functionality

 Step 3: For append and delete operations, store information about what was changed and how

 Step 4: For select and copy operations, track the selection range and clipboard content

 Step 5: For paste operations, handle replacing selected text or inserting at the end if no selection

Submitted Code :