C# Tutorial - Solving the turing.com coding challenge practise tests using C#

Source Code:

[davidodediran]

You have done a great job here, my brother. One thing I got from your presentation is the principle of separation of concern and understanding the actual questions or requirements is essential. I never thought I could access the last two indexes; I only knew of one in a list. Thanks for the method, and I am grateful.

[kaleemabdul]

You have done a great job, Your video is helping me to prepare for a C# challenge, Thank you.

int sum = 0;

ArrayList arrList = new ArrayList();

for (int i=0; i< ops.Length;i++)
{
int Num = 0;
sum = 0;
if (int.TryParse(ops[i], out Num))
{
arrList.Add(Num);
}
else if(ops[i]=="+")
{
sum =(int) arrList[arrList.Count - 1];
sum += (int)arrList[arrList.Count - 2];
arrList.Add(sum);
}
else if (ops[i] == "D")
{
sum = 2*(int)arrList[arrList.Count - 1];
arrList.Add(sum);
}
else if (ops[i] == "C")
{
- 1);
}
}
sum = 0;
for (int i = 0; i < arrList.Count; i++)
{
sum += (int)arrList[i];
}

return sum;

[ricardosilva]

Some tips: On the first problem It's possible to avoid the unnecessary nested loops: You can solve the problem with just one loop, which will give an O(n) algorithm. Also, try to use more meaningful names for variables. Don't forget to handle invalid inputs: It's not a good strategy to consider any input other than C, D, or + as an integer.

[lifeofintelligence]

I liked the solution very much
I've also tried one.

public int CalPointsFunc(string[] args)
{
int output;
List<int> record = new List<int>();
foreach(string arg in args)
{
if (Int32.TryParse(arg, out output))
{

}
else
{
if (arg == "C")
record.RemoveAt(record.Count - 1);
else if (arg == "D")
record.Add(record.Last() * 2);
else if (arg == "+")
- 2] + record.Last());
}
}
return record.Sum();
}

Thanks

[dr.kenedy-oltitia]

Wow! happy to discover your channel. I am preparing to take a Javascript live coding challenge, at least you have given me a hint of what to expect.

[tracybufazi]

Wow!!
Thànk you so much for this. Nice content 👌
The background music is perfect for learning.

[raymondjavel]

I really appreciate the background music. Helps my attention

[kennethihemadu]

Can't wait for the full C# course. Im interested in learning that language

[zeynephan]

Why is the music playing in the background when doing a fully concentrated work?

[nelsonmudanya]

I recreated your solution using much shorter syntax.
Here it is ...
class Solution
{
public int CalPoints(string[] ops)
{
var opsList = new List<int>();
var count = 0;
foreach(var op in ops)
{
if (op.Equals("+"))
{
var val = opsList[opsList.Count -1] + opsList[opsList.Count - 2];
opsList.Add(val);
}
else if (op.Equals("D"))
{
var val = opsList[opsList.Count - 1] * 2;
opsList.Add(val);
}
else if (op.Equals ("C"))
{
- 1);
}
else
{
opsList.Add(int.Parse(op));
}
}
foreach(var op in opsList)
{
count += op;
}
return count;
}
}
class CalPoints
{
public static void Main(string[] args)
{
var solution = new Solution();
var space = new Char[] { ' ' };
string[] ops =
int output = solution.CalPoints(ops);

}
}

[frankjames]

This is great content. Looking forward to try the live coding challenge in Kotlin

[okechukwuihechukwu]

Im looking forward to develop my skills in programming from your channel.Thanks

[lordgreat]

why didnt u make integer list you couldve only needed to parse once while adding right?

[huseyinsarioglu]

I try to write before watching your solution. Still refactor should be done. Here it is:

public int Calculate(string[] scores)
{
const string CANCEL = "C";
const string DOUBLE = "D";
const string ADD = "+";

if (scores == null || scores.Length == 0)
{
return 0;
}

var records = new List<int>();
foreach (var score in scores)
{
switch (score)
{
case CANCEL:
if(records.Count == 0) throw new Exception($"{CANCEL} operator cannot be used first!");
- 1);
continue;
case DOUBLE:
if (records.Count == 0) throw new Exception($"{DOUBLE} operator cannot be used first!");
records.Add(records[^1] * 2);
continue;
case ADD:
if (records.Count < 2) throw new Exception($"{ADD} operator cannot be used for first two values!");
records.Add(records[^1] + records[^2]);
continue;
default:
if (!int.TryParse(score, out int number))
{
throw new ArgumentException($"Unknown score specifier: {score}");
}
records.Add(number);
continue;
}
}

return records.Sum();
}

[robertovillavicencio]

I did something like that yesterday, un VS works ok but un the turing web give me a sintaxis error in " value.Count - 1 " for get the last member, specificly un the -

[tsunablast]

Ty for the video! Your explanation is great and is helping me to prepare for a C# challenge. Just a question, why not to put the foreach (var val in opsList) [...] segment outside all if statements instead of copying and repeating it for each of them? I may be missing something.

[clearz]

A stack version for fun

var opList = new[] { "5", "2", "C", "D", "+" };
var stk = new Stack<int>();

foreach(var op in opList)
{
switch(op)
{
case "+":
var lVal = stk.Pop();
var rVal = stk.Peek();
stk.Push(lVal);
stk.Push(lVal + rVal);
break;
case "C":
stk.Pop();
break;
case "D":
stk.Push(stk.Peek() * 2);
break;
default:
stk.Push(int.Parse(op));
break;
}
}
Console.WriteLine(stk.Sum());

[digitalizedhorizon]

Thanks it was great! and here is an other solution:
public static int CalPoints(string[] ops)
{
Stack<int> stack = new Stack<int>();

foreach (string op in ops)
{
if (int.TryParse(op, out int score))
{
stack.Push(score);
}
else if (op == "+")
{
int prev1 = stack.Pop();
int prev2 = stack.Peek();
int newScore = prev1 + prev2;
stack.Push(prev1);
stack.Push(newScore);
}
else if (op == "D")
{
int prev = stack.Peek();
stack.Push(prev * 2);
}
else if (op == "C")
{
stack.Pop();
}
}

int finalScore = 0;
while (stack.Count > 0)
{
finalScore += stack.Pop();
}

return finalScore;
}

[mgadriescu]

My solution, nice and clean
public int CalPoints(string[] ops)
{
var record = new List<int>();
foreach (var item in ops)
{
switch (item)
{
case var _ when int.TryParse(item, out int value):
record.Add(value);
break;
case "+":
record.Add(record[^2] + record[^1]);
break;
case "D" or "d":
record.Add(2 * record[^1]);
break;
case "C" or "c":
record.RemoveAt(record.Count - 1);
break;
}
}
return record.Sum();
}
}

[abdulrafeyartist]

Both can be done using single loop.

Solution 1 :
List<int> result = new List<int>();
for (int i = 0; i < ops.Length; i++)
{
if (ops[i] == "+")
{
- 1] + result[result.Count - 2]);
}
else if (ops[i] == "D")
{
- 1] * 2);
}
else if (ops[i] == "C")
{
result.RemoveAt(result.Count - 1);
}
else
{

}
}

return result.Sum();



Solution 2:
char[] chars = s.ToCharArray();
Stack<char> openParenthesis = new Stack<char>();

foreach (var c in chars)
{
if(c == '(' || c == '{' || c == '[')
{
openParenthesis.Push(c);
}

else if(c == ')')
{
if(openParenthesis.Peek() == '(')
{
openParenthesis.Pop();
}
}
else if(c == '}')
{
if (openParenthesis.Peek() == '{')
{
openParenthesis.Pop();
}
}
else if (c == ']')
{
if (openParenthesis.Peek() == '[')
{
openParenthesis.Pop();
}
}
}

return openParenthesis.Count == 0;