Solutions to DiverseArray problem on 2015 AP CompSci exam - https://compsci.rocks/diversearray-solution/

arraySum.java

public static int arraySum( int[] arr ) {
    int s = 0;
    for (int n: arr)
        s += n;
    return s;
}

public static int arraySum( int[] arr ) {
  int s = 0;
  for (int i=; i<arr.length; i++) {
    s += arr[i]
  }
  return s;
}

public static int arraySum( int[] arr ) {
  int s = 0;
  int pos = 0;
  while (pos < arr.length) {
    s += arr[pos];
    pos++;
  }
  return s;
}

isDiverse.java

public static boolean isDiverse( int[][] arr2D ) {
    /* To be implemented in Part C */
    int[] check = rowSums(arr2D);
    for (int i=0; i<check.length; i++) {
        for (int j=i+1; j<check.length; j++) {
            if (check[i] == check[j])
                return false; 
        }
    }
    return true; 
}

rowSums.java

public static int[] rowSums( int[][] arr2D ) {
    int[] out = new int[arr2D.length];
    for (int i=0; i<arr2D.length; i++)
        out[i] = arraySum(arr2D[i]); 
    return out; 
}