Description

You can check your solutions here: https://judge.softuni.bg/Contests/1445/Stacks-and-Queues-Lab
I. Working with Stacks
1. Reverse Strings
Write program that:
• Reads an input string
• Reverses it using a Stack<T>
• Prints the result back at the terminal
Examples
Input Output
I Love C# #C evoL I
Stacks and Queues seueuQ dna skcatS
Hints
• Use a Stack<string>
• Use the methods Push(), Pop()

2. Stack Sum
Write program that:
• Reads an input of integer numbers and adds them to a stack
• Reads commands until “end” is received
• Prints the sum of the remaining elements of the stack
Input
• On the first line you will receive an array of integers
• On the next lines, until the “end” command is given, you will receive commands – a single command and one or two numbers after the command, depending on what command you are given
• If the command is “add”, you will always receive exactly two numbers after the command which you need to add in the stack
• If the command is “remove”, you will always receive exactly one number after the command which represents the count of the numbers you need to remove from the stack. If there are not enough elements skip the command.
Output
• When the command “end” is received, you need to print the sum of the remaining elements in the stack
Examples
Input Output
1 2 3 4 adD 5 6
REmove 3 eNd Sum: 6
3 5 8 4 1 9 add 19 32 remove 10 add 89 22 remove 4 remove 3 end Sum: 16
Hints
• Use a Stack<int>
• Use the methods Push(), Pop()
3. Simple Calculator
Create a simple calculator that can evaluate simple expressions with only addition and subtraction. There will not be any parentheses.
Solve the problem using a Stack.
Examples
Input Output
2 + 5 + 10 – 2 – 1 14
2 – 2 + 5 5
Hints
• Use a Stack<string>
• You can either o add the elements and then Pop() them out o or Push() them and reverse the stack
4. Matching Brackets
We are given an arithmetic expression with brackets. Scan through the string and extract each sub-expression.
Print the result back at the terminal.
Examples
Input Output
1 + (2 – (2 + 3) * 4 / (3 + 1)) * 5 (2 + 3)
(3 + 1)
(2 – (2 + 3) * 4 / (3 + 1))
(2 + 3) – (2 + 3) (2 + 3)
(2 + 3)
Hints
• Scan through the expression searching for brackets o If you find an opening bracket, push the index into the stack o If you find a closing bracket pop the topmost element from the stack. This is the index of the opening bracket.
o Use the current and the popped index to extract the sub-expression
II. Working with Queues
5. Print Even Numbers
Write program that:
• Reads an array of integers and adds them to a queue
• Prints the even numbers separated by “, ”
Examples
Input Output
1 2 3 4 5 6 2, 4, 6
11 13 18 95 2 112 81 46 18, 2, 112, 46
Hints
• Use a Queue<int>
• Use the methods Enqueue(), Dequeue(), Peek()
6. Supermarket
Reads an input consisting of a name and adds it to a queue until “End” is received. If you receive “Paid”, print every customer name and empty the queue, otherwise we receive a client and we have to add him to the queue. When we receive “End” we have to print the count of the remaining people in the queue in the format: “{count} people remaining.”.
Examples
Input Output
Gosho
Pesho
Ivan
Paid
Nasko
Stefan
Naska
Tanq
End Gosho
Pesho
Ivan
4 people remaining.
Ani
Miro
Stoyan 3 people remaining.
End
7. Hot Potato
Hot potato is a game in which children form a circle and start passing a hot potato. The counting starts with the fist kid. Every nth toss the child left with the potato leaves the game. When a kid leaves the game, it passes the potato along. This continues until there is only one kid left.
Create a program that simulates the game of Hot Potato. Print every kid that is removed from the circle. In the end, print the kid that is left last.
Examples
Input Output
Mimi Pepi Toshko 2 Removed Pepi
Removed Mimi
Last is Toshko
Gosho Pesho Misho Stefan Krasi 10 Removed Krasi
Removed Pesho
Removed Misho
Removed Gosho
Last is Stefan
Gosho Pesho Misho Stefan Krasi 1 Removed Gosho
Removed Pesho
Removed Misho
Removed Stefan
Last is Krasi
8. Traffic Jam
Create a program that simulates the queue that forms during a traffic jam. During a traffic jam only N cars can pass the crossroads when the light goes green. Then the program reads the vehicles that arrive one by one and adds them to the queue. When the light goes green N number of cars pass the crossroads and for each a message “{car} passed!” is displayed. When the “end” command is given, terminate the program and display a message with the total number of cars that passed the crossroads.
Input
• On the first line you will receive N – the number of cars that can pass during a green light
• On the next lines, until the “end” command is given, you will receive commands – a single string, either a car or “green”
Output
• Every time the “green” command is given, print out a message for every car that passes the crossroads in the format “{car} passed!”
• When the “end” command is given, print out a message in the format “{number of cars} cars passed the crossroads.”
Examples
Input Output
4 Hummer H2 passed!
Hummer H2
Audi
Lada
Tesla
Renault
Trabant
Mercedes MAN Truck green green Tesla
Renault Trabant end Audi passed!
Lada passed!
Tesla passed!
Renault passed!
Trabant passed!
Mercedes passed!
MAN Truck passed!
8 cars passed the crossroads.
3
Pesho’s car
Gosho’s car
Mercedes CLS Nekva troshka
green BMW X5 green end Pesho’s car passed!
Gosho’s car passed!
Mercedes CLS passed!
Nekva troshka passed!
BMW X5 passed!
5 cars passed the crossroads.