Pascal's Triangle II — LeetCode 119 Python Solution

The problem

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:

This statement is abridged. Read the full problem on LeetCode.

Example

Input

rowIndex = 3

Output

[1,3,3,1]

Python solution

class Solution:
    def getRow(self, rowIndex: int) -> List[int]:
        f = [1] * (rowIndex + 1)
        for i in range(2, rowIndex + 1):
            for j in range(i - 1, 0, -1):
                f[j] += f[j - 1]
        return f

Complexity

Pattern: Dynamic Programming

Define a state, write the transition, and stop recomputing the same subproblem. LeetCode 119. Pascal's Triangle II is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Dynamic Programming.

The dynamic programming guide has the Python template for the pattern and the 481 LeetCode problems that use it.

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