不想写第二遍的刷题笔记

世界级打野都是rush大龙的

Pascal's Triangle II

LeetCode 119

Given a non-negative index k where k ≤ 33, return the kth index row of the Pascal’s triangle.

Note that the row index starts from 0.

In Pascal’s triangle, each number is the sum of the two numbers directly above it.

Example:

Input: 3
Output: [1,3,3,1]

Follow up:

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

Solution

class Solution(object):
def getRow(self, rowIndex):
"""
:type rowIndex: int
:rtype: List[int]
"""
row_p = [1]
row = [1]
for i in range(0, rowIndex):
row = [1]
for j in range(0, i):
row.append(row_p[j] + row_p[j+1])
row.append(1)
row_p = row
return row