README.md

118. Pascal's Triangle

Given a non-negative integer numRows, generate the first numRows of Pascal's triangle.

In Pascal's triangle, each number is the sum of the two numbers directly above it.

Example 1:

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

Solutions (Python)

1. Solution

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