mirror of
https://github.com/TheAlgorithms/Ruby
synced 2024-12-25 21:58:57 +01:00
45 lines
746 B
Ruby
45 lines
746 B
Ruby
# Given an integer row_index, return the rowIndexth (0-indexed) row of the Pascal's triangle.
|
|
|
|
# Example 1:
|
|
#
|
|
# Input: row_index = 3
|
|
# Output: [1,3,3,1]
|
|
#
|
|
# Example 2:
|
|
#
|
|
# Input: row_index = 0
|
|
# Output: [1]
|
|
#
|
|
# Example 3:
|
|
#
|
|
# Input: row_index = 1
|
|
# Output: [1,1]
|
|
|
|
# Complexity Analysis
|
|
#
|
|
# Time complexity: O(k).
|
|
# Space complexity: O(k).
|
|
|
|
def get_row(row_index)
|
|
(0..row_index).map { |num| combination(row_index, num) }
|
|
end
|
|
|
|
def combination(num1, num2)
|
|
factorial(num1) / (factorial(num2) * factorial(num1 - num2))
|
|
end
|
|
|
|
def factorial(num)
|
|
(1..num).inject(1) { |res, i| res * i }
|
|
end
|
|
|
|
row_index = 3
|
|
print(get_row(row_index))
|
|
# => [1,3,3,1]
|
|
|
|
row_index = 0
|
|
print(get_row(row_index))
|
|
# => [1]
|
|
|
|
row_index = 1
|
|
print(get_row(row_index))
|
|
# => [1,1]
|