tsanmmmm2000's Tech Blog

Question

Given numRows, generate the first numRows of Pascal's triangle.

For example, given numRows = 5,
Return

[
     [1],
    [1,1],
   [1,2,1],
  [1,3,3,1],
 [1,4,6,4,1]
]

My C# Solution

public class Solution {
    public IList<IList<int>> Generate(int numRows) {
        var result = new List<IList<int>>();
        IList<int> row = new List<int>();
        while(numRows > 0)
        {
            row = GenNextRow(row);
            result.Add(row);
            numRows--;
        }
        return result;
    }
    
    private IList<int> GenNextRow(IList<int> row)
    {
        var nextRow = new List<int>();
        nextRow.Add(1);
        if (row.Count > 0)
        {
            for(var i = 0; i < row.Count - 1; i++)
            {
                var val = row[i] + row[i+1];
                nextRow.Add(val);
            }
            nextRow.Add(1);           
        }
        return nextRow;
    }
}