Undo Text Editor

Write a program that simulates a tiny text editor with undo. Read commands from standard input until the input ends. Each command is on its own line and is one of:
- add WORD — push WORD (a single word with no spaces) onto a stack<string>
- undo — remove the most recently added word; if there are no words, do nothing
- print — print all current words in the order they were added (oldest first, newest last), separated by single spaces, followed by a newline; if there are no words print the line (empty)

Only print produces output.

Input example:
add hello
add world
print
undo
print

Expected Output:

hello world↵
hello↵
(empty)↵
a b↵

= newline. The output ends with a newline — print one after the last line.

Hints4 available

Topics:

STL ContainersStacks

Code Editor

Tab to indent (Esc then Tab to move on) · Ctrl+Enter to run · Shift+Alt+F to format · Ctrl+Space to expand shortcuts (cout, fori)

Your Output

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Test Cases

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