题目内容：

The triangls is made up of number.The first line is 1 The second line is 1 1 The third line is
The triangls is made up of number.The first line is 1
The second line is 1 1
The third line is 1 2 1
What is the third number in line 1994?1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
.

优质解答

二项式展开,一下子搞定
1993*1992/2