Simple Text Editor| Stack
TASK(medium)
Implement a simple text editor. The editor initially contains an empty string. Perform operations of the following types:
- append - Append string to the end of.
- delete - Delete the last characters of.
- print - Print the character of.
- undo - Undo the last (not previously undone) operation of type or, reverting to the state it was in prior to that operation.
Example
operation
index S ops[index] explanation
----- ------ ---------- -----------
0 abcde 1 fg append fg
1 abcdefg 3 6 print the 6th letter - f
2 abcdefg 2 5 delete the last 5 letters
3 ab 4 undo the last operation, index 2
4 abcdefg 3 7 print the 7th characgter - g
5 abcdefg 4 undo the last operation, index 0
6 abcde 3 4 print the 4th character - d
The results should be printed as:
f
g
d
Input Format
The first line contains an integer, Q, denoting the number of operations.
Each line i of the Q subsequent lines (where 0<i<Q) defines an operation to be performed. Each operation starts with a single integer, t(where t € {1,2,3,4}), denoting a type of operation as defined in the Problem Statement above. If the operation requires an argument, is followed by its space-separated argument. For example, if and, line will be 1 abcd.
Constraints
1<=Q<=106
1<=K<=|S|
The sum of the lengths of all W in the input 106.
The sum of k over all delete operations <=2106.
All input characters are lowercase English letters.
It is guaranteed that the sequence of operations given as input is possible to perform.
Output Format
Each operation of type 3 must print the kth character on a new line.
Sample Input
STDIN Function
----- --------
8 Q = 8
1 abc ops[0] = '1 abc'
3 3 ops[1] = '3 3'
2 3 ...
1 xy
3 2
4
4
3 1
Sample Output
c
y
a
SOLUTION 1
n = int(input())
data = str()
log = list()
for i in range(n):
operator = input()
if len(operator.split()) == 2:
op, w = operator.split()
if op == '1':
log.append(data)
data += w
elif op == '2':
log.append(data)
data = data[:-int(w)]
elif op == '3':
print(data[int(w) - 1])
else:
data = log.pop()
Explanation Steps
1. Initialization: text variable is initialized as an empty string to store the text content.
2. Menu: A simple menu is displayed using print statements, allowing the user to choose between inserting text (1), deleting text (2), displaying text (3), or exiting (4).
3. Operations:
- Insert Text: Appends the user-entered text (insert_text) to the text variable.
- Delete Text: Uses string slicing (text[:start_index] + text[start_index + length:]) to delete a specified portion of text based on user input (start_index and length).
- Display Text: Prints the current content of the text variable.
- Exit: Breaks out of the while loop and exits the program.
4. Error Handling: Basic input validation is implemented to ensure the user enters valid choices and inputs for delete operations.
