打印出以下的杨辉三角形

每一行的第一个和最后一个都是1，而中间元素是由表达式 a[i][j] =a[i-1][j-1] + a[i-1][j] 计算出来。因为要使用上面的数据，这样我们想到了用二维数组进行数据的存储。-Print out the following Triangle (requires print line 10) the first and last of each line 1, the middle element is the expression a [i] [j] = a [i-1] [j-1]+ a [i-1] [j] is calculated. To use the above data, so we thought of the two-dimensional array for data storage.