BadNeighbors

BadNeighbors.java

public class BadNeighbors {

    public static void main(String[] args) {
        int[] collections = new int[args.length];
        for (int i=0; i<args.length; ++i) {
            collections[i] = Integer.parseInt(args[i]);
        }
        System.out.printf("%d\n", maxDonations(collections));
    }

    public static int maxDonations(int[] donations) {
        final int n = donations.length;
        if (n == 0) return 0;
        if (n == 1) return donations[0];
        if (n == 2) return Math.max(donations[0], donations[1]);
        int[] zero = new int[n];
        int[] one = new int[n];
        zero[0] = donations[0];
        zero[1] = Math.max(donations[1], donations[0]);
        one[0] = 0;
        one[1] = donations[1];
        for (int i=2; i+1<n; ++i) {
            zero[i] = Math.max(zero[i-1], zero[i-2] + donations[i]);
            one[i] = Math.max(one[i-1], one[i-2] + donations[i]);
        }
        zero[n-1] = zero[n-2];
        one[n-1] = Math.max(one[n-3] + donations[n - 1], one[n-2]);
        return Math.max(zero[n-1], one[n-1]);
    }
}