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A 3×3 board is given as three strings of X, O and . (empty). A player wins with three of their marks in a row, column or diagonal. Boards never have two winners.
Implement tic_tac_toe_winner(board).
Input
board: Three rows of three characters each.
Output
Return "X" or "O" for the winner, "Draw" if the board is full with no winner, or "Pending" if empty cells remain and nobody has won.
Constraints
board has exactly 3 rows of length 3
Examples
Example 1
Input:
board = ["XOX", ".X.", "O.X"]
Expected output:
"X"Explanation
X holds the diagonal from top-left to bottom-right, so X wins.
Example 2
Input:
board = ["XOX", "XOO", "OXX"]
Expected output:
"Draw"Explanation
The board is full and no line has three of a kind: Draw.
References
-
Example 1 Not runInput:
board = ["XOX", ".X.", "O.X"]Expected output:"X"Your output -
Example 2 Not runInput:
board = ["XOX", "XOO", "OXX"]Expected output:"Draw"Your output
5 hidden tests also run when you submit.
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🔷 About This C# / .NET Online Executor
The CodeUtility C# Executor lets you write and run real C# code directly in your browser - no installation, Visual Studio setup, or .NET SDK required. It’s powered by a secure sandbox that supports the .NET runtime and modern C# language versions, including C# 9 and later.
This tool uses dotnet-script under the hood to compile and execute your code with true .NET behavior, allowing you to experiment with both basic and advanced C# features like LINQ, async/await, pattern matching, and generics.
You can test simple scripts, functions, and logic flows, or explore concepts like classes, structs, inheritance, and interfaces - all in a clean, distraction-free coding environment.
Whether you’re learning C#, testing algorithms, or experimenting with .NET features, the CodeUtility C# Executor gives you a fast, secure, and reliable way to run C# code instantly from any browser.
More than a code runner
Use a multi-file editor, an isolated execution terminal, runtime-specific libraries, persistent workspaces, sharing, and real-time collaboration from the same executor.
How to use this executor?
Choose a runtime, open or create a file, write your code, and select Run. Output appears in the terminal, while signed-in users can keep files in a workspace, install libraries, and collaborate through shares.
- Select a version and edit the current file or open another workspace file.
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💡 C# Basics & Examples You Can Try Above
1. Declaring Variables and Constants
C# uses strongly-typed variable declarations. Use const for compile-time constants and readonly for runtime constants.
int age = 30;
double pi = 3.14159;
char grade = 'A';
string name = "Alice";
bool isActive = true;
// Constants
const int MaxUsers = 100;
const string Company = "CodeUtility";2. Conditionals (if / switch)
Use if, else if, and switch for control flow.
int x = 2;
if (x == 1)
{
Console.WriteLine("One");
}
else if (x == 2)
{
Console.WriteLine("Two");
}
else
{
Console.WriteLine("Other");
}
switch (x)
{
case 1:
Console.WriteLine("One");
break;
case 2:
Console.WriteLine("Two");
break;
default:
Console.WriteLine("Other");
break;
}3. Loops
C# supports for, while, and foreach loops.
for (int i = 0; i < 3; i++)
{
Console.WriteLine(i);
}
int n = 3;
while (n > 0)
{
Console.WriteLine(n);
n--;
}4. Arrays
Arrays store fixed-size collections of elements of the same type.
int[] numbers = { 10, 20, 30 };
Console.WriteLine(numbers[1]);5. List Manipulation
Use List<T> for dynamic collections.
List<int> nums = new List<int> { 1, 2, 3 };
nums.Add(4);
nums.Remove(2);
foreach (int n in nums)
{
Console.Write(n + " ");
}6. Console Input/Output
Use Console.WriteLine and Console.ReadLine for basic I/O.
Console.Write("Enter your name: ");
string name = Console.ReadLine();
Console.WriteLine($"Hello, {name}!");7. Functions
Define methods using a return type, name, and parameters.
int Add(int a, int b)
{
return a + b;
}
Console.WriteLine(Add(3, 4));8. Dictionaries
Dictionary<TKey, TValue> stores key-value pairs.
Dictionary<string, int> ages = new Dictionary<string, int>();
ages["Alice"] = 30;
Console.WriteLine(ages["Alice"]);9. Exception Handling
Handle runtime errors using try, catch, and finally.
try
{
throw new Exception("Something went wrong");
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}10. File I/O
Use File and StreamReader/StreamWriter for file operations.
File.WriteAllText("file.txt", "Hello File");
string text = File.ReadAllText("file.txt");
Console.WriteLine(text);11. String Manipulation
C# strings support methods like Length, Substring, Contains.
string message = "Hello World";
Console.WriteLine(message.Length);
Console.WriteLine(message.Substring(0, 5));
Console.WriteLine(message.Contains("World"));12. Classes & Objects
C# supports object-oriented programming through classes and objects.
class Person
{
public string Name;
public Person(string name) => Name = name;
public void Greet() => Console.WriteLine($"Hi, I'm {Name}");
}
Person p = new Person("Alice");
p.Greet();