Ctrl + Z | Practice Problems

Ctrl + Z

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Problem

Problem Description

For this problem, you will create a standard undo function.
 An undo function allows a user to reverse or unperform the effect of an earlier action.

Input Format

The input file consists of logs describing a series of actions performed. The logs may contain the string "Ctrl+Z" in which case you would have to undo the most recently performed action.

Output Format

Output a single string - the currently latest action performed after all actions and undos. If there are no available actions to undo after the series of operations, print "No actions in clipboard." without the quotations.

Constraints

Each action log $A$ is $1 < |A| < 50$
Log file $L$ will consist of $t$ lines where $1 < t < 100$ .

Sample Input

Delete colors from lines
Update size of images in layer 1
Create box in separate layer
Delete all lines with gradient
Ctrl+Z
Ctrl+Z
Group together all red lines
Ctrl+Z
Ctrl+Z

Sample Output

Delete colors from lines

Time Limit: 1

Memory Limit: 256

Source Limit: