1354. Pascal’s Triangle II
Description:
Given a non-negative index k where k ≤ 33, return the kth index row of the Pascal’s triangle.
Example
Example:
Input: 3
Output: [1,3,3,1]
Challenge
Could you optimize your algorithm to use only O(k) extra space?
Code:
class Solution:
"""
@param rowIndex: a non-negative index
@return: the kth index row of the Pascal's triangle
"""
def getRow(self, rowIndex):
# write your code here
def pascal(index, preRow):
curRow = [1]
for i in range(index-1):
curRow.append(preRow[i]+preRow[i+1])
curRow.append(1)
return curRow
secondRow = [1,1]
tmpRow = secondRow
if rowIndex == 1:
return secondRow
for i in range(2, rowIndex+1):
tmpRow = pascal(i, tmpRow)
return tmpRow