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Generate the Pascal’s Triangle

Certification: Basic Level Accuracy: 100% Submissions: 2 Points: 5

Write a C# program to generate Pascal's triangle up to 'n' rows. In Pascal's triangle, each number is the sum of the two numbers directly above it. The first row is always [1], and the first and last elements of each subsequent row are always 1.

Example 1
    
        
  • Input: numRows = 5
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  • Output: [[1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1]]
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  • Explanation:
            
      
                
    • Step 1: Create a list of lists to store the triangle rows.
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    • Step 2: Add the first row [1] to the result.
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    • Step 3: For row 2: Start with 1, end with 1. Result: [1,1]
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    • Step 4: For row 3: Start with 1, calculate middle value 1+1=2, end with 1. Result: [1,2,1]
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    • Step 5: For row 4: Start with 1, calculate middle values 1+2=3 and 2+1=3, end with 1. Result: [1,3,3,1]
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    • Step 6: For row 5: Start with 1, calculate middle values 1+3=4, 3+3=6, and 3+1=4, end with 1. Result: [1,4,6,4,1]
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Example 2
    
        
  • Input: numRows = 3
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  • Output: [[1], [1,1], [1,2,1]]
    • 
        
  • Explanation:
            
      
                
    • Step 1: Create a list of lists to store the triangle rows.
      • 
                
    • Step 2: Add the first row [1] to the result.
      • 
                
    • Step 3: For row 2: Start with 1, end with 1. Result: [1,1]
      • 
                
    • Step 4: For row 3: Start with 1, calculate middle value 1+1=2, end with 1. Result: [1,2,1]
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Constraints
    
        
  • 1 ≤ numRows ≤ 30
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  • Time Complexity: O(n²)
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  • Space Complexity: O(n²)
    •
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Hint
Solution

Solution Hints

    
  
  • Use a list of lists to store each row of the triangle
    • 
  
  • Always start each row with 1
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  • Calculate the middle elements of each row using the values from the previous row
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  • Always end each row with 1
    • 
  
  • Build each row based on the previous row
    •

Steps to solve by this approach:

 Step 1: Create a result list to store all rows of Pascal's triangle.
 Step 2: Add the first row [1] to the result.
 Step 3: For each subsequent row, start with 1.
 Step 4: Calculate middle elements by adding the two elements above from the previous row.
 Step 5: End each row with 1 and add the completed row to the result.

Submitted Code :