119. Pascal's Triangle II
Đề Bài
Given an integer rowIndex, return the rowIndexth (0-indexed) row of the Pascal's triangle.
In Pascal's triangle, each number is the sum of the two numbers directly above it as shown:
Example 1:
Input: rowIndex = 3 Output: [1,3,3,1]
Example 2:
Input: rowIndex = 0 Output: [1]
Example 3:
Input: rowIndex = 1 Output: [1,1]
Constraints:
0 <= rowIndex <= 33
Follow up: Could you optimize your algorithm to use only O(rowIndex) extra space?
Lời Giải
Python
0119-pascals-triangle-ii.py
class Solution:
def getRow(self, rowIndex: int) -> List[int]:
ans = []
for i in range(rowIndex + 1):
tmp = [1] * (i + 1)
for j in range(1, i):
tmp[j] = ans[i - 1][j - 1] + ans[i - 1][j]
ans.append(tmp)
return ans[rowIndex]