leetcode -- Pascal's Triangle -- 简单

https://leetcode.com/problems/pascals-triangle/

就是几个循环而已。很简单

class Solution(object):
    def generate(self, numRows):
        """ :type numRows: int :rtype: List[List[int]] """
        if numRows == 0:
            return []
        elif numRows == 1:
            return [[1]]
        elif numRows == 2:
            return [[1],[1,1]]


        reslist = [[1],[1,1]]

        for i in xrange(2, numRows):
            mylist = [1]

            for j in xrange(1, i):
                tmp = sum(reslist[i - 1][j - 1 : j + 1])
                mylist.append(tmp)

            mylist.append(1)

            reslist.append(mylist)

        return reslist