Max Sum Without Adjacent Elements

Given a 2 x N grid of integer, A, choose numbers such that the sum of the numbers is maximum and no two chosen numbers are adjacent horizontally, vertically or diagonally, and return it.

Note: You can choose more than 2 numbers.

Input Format:

The first and the only argument of input contains a 2d matrix, A.

Output Format:

Return an integer, representing the maximum possible sum.

Constraints:

1 <= N <= 20000
1 <= A[i] <= 2000

Example:

Input 1:
    A = [   [1]
            [2]    ]

Output 1:
    2

Explanation 1:
    We will choose 2.

Input 2:
    A = [   [1, 2, 3, 4]
            [2, 3, 4, 5]    ]
    
Output 2:
    We will choose 3 and 5.

public class Solution {
    public int adjacent(int[][] A) {
        if (A[0].length == 1)
            return Math.max(A[0][0], A[1][0]);
        int m = A[0].length;
        // 0th index best
        int prev_max = Math.max(A[0][0], A[1][0]);
        // 1st index best
        int curr_max = Math.max(prev_max, Math.max(A[0][1], A[1][1]));
        for (int j = 2; j < m; j++) {
            int temp = curr_max;
            curr_max = Math.max(Math.max(A[0][j], A[1][j]) + prev_max, curr_max);
            prev_max = temp;
        }
        return curr_max;
    }
}