Pascal's Triangle


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]
]
Solution:

 This one is easy.

The following code passes LeetCode Online Large Judge.
Redo it at Aug. 24, 2013. BUG free.

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