using System;
using System.Linq;
public class Test
{
public static void Main()
{
var data = new string[] {"a", "b", "c", "d"};
var triangle = Enumerable
.Range(1, data.Length)
.Select(row => data.Take(row).ToList())
.ToList();
foreach (var r in triangle) {
foreach (var c in r) {
Console.Write("{0} ", c);
}
Console.WriteLine();
}
}
}
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