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