How to Solve Pascal’s Triangle in Python

The challenge

Given an integer numRows, return the first numRows of Pascal’s triangle.

In Pascal’s triangle, each number is the sum of the two numbers directly above it as shown:

Example 1:

Input: numRows = 5
Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

Example 2:

Input: numRows = 1
Output: [[1]]

Constraints:

• 1 <= numRows <= 30

The solution in Python code

class Solution:
    def generate(self, numRows: int) -> List[List[int]]:
        triangle = [[1]]
        
        for j in range(1, numRows):
            prev = triangle[-1]
            triangle.append([1] + [prev[i]+prev[i+1] for i in range(len(prev)-1)] + [1])
            
        return triangle