leetcode解题-pascal triangle


描述

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]
]

分析

比较简单,打印杨辉三角。

代码

Python

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class (object):
def generate(self, numRows):
"""
:type numRows: int
:rtype: List[List[int]]
"""

if numRows == 0:
return []
rs = [[1]]
for i in xrange(1, numRows):
row = [1]
for j in xrange(1, i):
row.append(rs[i - 1][j - 1] + rs[i - 1][j])
row.append(1)
rs.append(row)
return rs