119. Pascal's Triangle II

https://leetcode.com/problems/pascals-triangle-ii

Python

Recursive

class Solution:
    def getRow(self, rowIndex: int) -> List[int]:
        if rowIndex == 0:
            return [1]
        if rowIndex == 1:
            return [1, 1]

        return self._generate(2, rowIndex, [1, 1])

    def _generate(self, level, target_level, pre_level):
        if level > target_level:
            return pre_level

        current = [1]
        for i in range(1, len(pre_level)):
            pre = pre_level[i-1]
            cur = pre_level[i]
            current.append(pre+cur)
        current.append(1)

        return self._generate(level+1, target_level, current)