Leetcode with Python, Array

118 Pascal ' s Triangle

Given numrows, generate the first numrows of Pascal ' s triangle.

For example, given numrows = 5,
Return

[     1], [    1,2,1], [   1,3,3,1], [  1,4,6,4,1]

Class solution (Object):    def generate (self, numrows): "" "        : Type Numrows:int        : Rtype:list[list[int]] "" "        res = [[1]] for        i in range (1,numrows):            res + = [Map (lambda X, y:x+y,res[-1]+[0],[0]+res[-1])]        return res[:numrows]        # [[1]]+[0] [[1],0] # [[    1]]+[0,1]->[[1],0,1] # [[1]]+[[0]]-[    [1],[0]]    # [[1]]+0] Error    # The code is elegant, but slow. The reason lies in the fact that it generates too much L ist while looping    # being careful when NumRows is 0, Res[:numrows] would return [] when it happens

119 Pascal ' s Triangle II

Given an index K, return the kth row of the Pascal ' s triangle.

For example, given k = 3,
Return [1,3,3,1] .

Note:
Could optimize your algorithm to use only O(k) extra space?

Class solution (Object):    def getRow (self, RowIndex): "" "        : Type Rowindex:int        : rtype:list[int]        " " "                res = [1] for        I in range (0, RowIndex):            res = [i+j for i,j in Zip (res + [0], [0] + res)]        return RES
   # list can ' t be added elementwisely with +

Leetcode with Python, Array