递推办法求第n行杨辉三角的系数

第n+1行杨辉三角的系数是C(n,0)+C(n,1)+...+C(n,n)，直接用这种办法计算的话速度会慢些。用递推法速度会快些。

下面是递推算法：

using System;


public class Triangle ...{
    public static void Main()
    ...{
        Triangle t=new Triangle();
        for (int i=1;i<15;i++)
            t.PrintTriangle1(i);
    }

    void PrintTriangle1(int n)
    ...{
        if( 1==n ) Console.WriteLine("{0}",1);
        else if( 2==n ) Console.WriteLine("{0},{1}",1,1);
        else ...{
            int[] a=new int[n];
            int[] b=new int[n];
            a[0]=1;
            a[1]=1;
            for(int i=3;i<=n;i++)...{
                b[0]=1;
                for(int k=1;k<=i-2;k++)...{
                    b[k]=a[k-1]+a[k];
                }
                b[i-1]=1;
                for(int j=0;j<n;j++)
                    a[j]=b[j];
            }
            for(int i=0;i<n-1;i++)
                Console.Write("{0},",a[i]);
            Console.Write(a[n-1]);
            Console.WriteLine();
        }   
    }
}