【LeetCode with Python】 Pascal's Triangle II

博客域名：http://www.xnerv.wang

原题页面：https://oj.leetcode.com/problems/pascals-triangle-ii/

题目类型：

难度评价：★

本文地址：/article/1377503.html

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 you optimize your algorithm to use only O(k) extra space?

class Solution:
    # @return a list of lists of integers
    def getRow(self, rowIndex):
        if rowIndex <= 0:
            return [1]
        elif 1 == rowIndex:
            return [1, 1]
        elif rowIndex >= 2:
            need_rowsnum = rowIndex - 1
            last_row = [1, 1]
            for i in range(0, need_rowsnum):
                new_row = [1]
                for j in range(1, len(last_row)):
                    new_row.append(last_row[j - 1] + last_row[j])
                new_row.append(1)
                last_row = new_row
            return last_row