[leetcode]Pascal's Triangle @ Python

原题地址：https://oj.leetcode.com/problems/pascals-triangle/

题意：

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]
]

解题思路：杨辉三角的求解。

代码：

class Solution:
    # @return a list of lists of integers
    def generate(self, numRows):
        if numRows == 0:
            return []
        if numRows == 1:
            return [[1]]
        if numRows == 2:
            return [[1], [1, 1]]
        if numRows > 2:
            list = [[] for i in range(numRows)]
            for i in range(0, numRows):
                list[i] = [1 for j in range(i + 1)]
            for i in range(2, numRows):
                for j in range(1, i):
                    list[i][j] = list[i - 1][j - 1] + list[i - 1][j]
            return list