### LANGUAGE: JAVA

### CHALLENGE:

The sum of an array of size 0 is 0;

Otherwise, the sum of the first n elements of an array is the sum of the last of these added to the sum of the previous n-1 elements.

Write an int method named sum that accepts an integer array, and the number of elements in the array and returns the sum of the elements of the array.

### SOLUTION:

public static int sum( int[] arr, int len ){ if( len == 0 ) return 0; else return arr[len-1] + sum( arr, len-1 ); }