Pascal Triangle

Given numRows, generate the first numRows of Pascal’s triangle.

Pascal’s triangle : To generate A[C] in row R, sum up A’[C] and A’[C-1] from previous row R - 1.

Example:

Given numRows = 5,

Return

[
     [1],
     [1,1],
     [1,2,1],
     [1,3,3,1],
     [1,4,6,4,1]
]

public class Solution {
    public int[][] solve(int A) {
        int[][] arr = new int[A][];
        for (int i = 0; i < A; i++) {
            arr[i] = new int[i + 1];
            for (int j = 0; j <= i; j++) {
                if (j == 0 || j == i)
                    arr[i][j] = 1;
                else
                    arr[i][j] = arr[i - 1][j] + arr[i - 1][j - 1];
            }
        }
        return arr;
    }
}