118. 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]
]
My Solution
class Solution(object):
def generate(self, numRows):
"""
:type numRows: int
:rtype: List[List[int]]
"""
if numRows == 0:
return []
if numRows == 1:
return [[1]]
if numRows == 2:
return [[1], [1, 1]]
result, sub = [[1], [1, 1]], [1]
for i in range(2, numRows):
for j in range(1, i):
sub.append(result[i-1][j-1] + result[i-1][j])
sub.append(1)
result.append(sub)
sub = [1]
return result
Reference (轉(zhuǎn))
def generate(self, numRows):
res = [[1]]
for i in range(1, numRows):
res += [map(lambda x, y: x+y, res[-1] + [0], [0] + res[-1])]
return res[:numRows]
Example:
1 3 3 1 0
+ 0 1 3 3 1
= 1 4 6 4 1