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119-pascals-triangle-ii.py
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119-pascals-triangle-ii.py
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# class Solution:
# def getRow(self, rowIndex: int) -> List[int]:
# pascal_list = [1]
#
# for row in range(1, rowIndex + 1):
# # previous row
# prev_pascal_list = pascal_list
#
# pascal_list = []
# # new row: numCol = len(prev_pascal_list) + 1
# for col in range(len(prev_pascal_list) + 1):
# if col == 0 or col == len(prev_pascal_list):
# pascal_list.append(1)
# else:
# pascal_list.append(prev_pascal_list[col-1] + prev_pascal_list[col])
#
# return pascal_list
# recursive
class Solution:
def getRow(self, rowIndex: int) -> List[int]:
pascal_list = self.helper(rowIndex, [1])
return pascal_list
def helper(self, rowIndex, pascal_list):
if ((rowIndex + 1) == len(pascal_list)):
return pascal_list
prev_pascal_list = pascal_list
pascal_list = []
for col in range(len(prev_pascal_list) + 1):
if col == 0 or col == len(prev_pascal_list):
pascal_list.append(1)
else:
pascal_list.append(prev_pascal_list[col-1] + prev_pascal_list[col])
ans = self.helper(rowIndex, pascal_list)
return ans