Question

Assume arr2 is declared as a two-dimensional array of integers. Which of the following segments of code successfully calculates the sum of all elements arr2?

1. int sum = 0;
   for(int j = 0; j < arr2.length; j++)
   {
      for(int k = 0; k < arr2[j].length; k++)
      {
         sum += arr2[k][j];
      }
   }
2. int sum = 0;
   for(int j = arr2.length − 1; j >= 0; j−−)
   {
      for(int k = 0; k < arr2[j].length; k++)
      {
         sum += arr2[j][k];
      }
   }
3. int sum = 0;
   for(int[] m : arr2)
   {
      for(int n : m)
      {
         sum += n;
      }
   }

Answer 1

2 and 3

2)

int sum = 0;
for(int j = arr2.length − 1; j >= 0; j−−)
{
   for(int k = 0; k < arr2[j].length; k++)
   {
      sum += arr2[j][k];
   }
}

3)

int sum = 0;
for(int[] m : arr2)
{
   for(int n : m)
   {
      sum += n;
   }
}