CareerCup

def difference(numbers):
output = []
for i in range(len(numbers) - 1):
output.append(numbers[i+1] - numbers[i])
return output

numbers = [787668, 787787, 787948, 787980, 788094, 788124]

print difference(numbers)

def difference(numbers):
    output = []
    for i in range(len(numbers) - 1):
        output.append(numbers[i+1] - numbers[i])
    return output

numbers = [787668, 787787, 787948, 787980, 788094, 788124]

print difference(numbers)

public static void main(String[] args) {
		int[] main = {10,40,78,98};
		int[] result = new int[main.length-1];
		
		for(int i = 0; i<main.length-1; i++){
			result[i] = main[i+1]-main[i];
		}
		
		for(int i = 0; i<result.length; i++){
			System.out.println(result[i]);
		}
	}

A few things already missed big time:
1. What if there are no numbers at all?
2. What if we do not know the number of numbers e.g. they are in a file?
3. The output does not look like the requested (e.g. no , between the numbers, and there isn't one at the end

public static void printOutput(InputStream inputStream) {
        Scanner scanner = new Scanner(inputStream);

        List<Long> numbers = new ArrayList<Long>();
        while (scanner.hasNext()) {
            numbers.add(scanner.nextLong());
        }

        int numNumbers = numbers.size();
        if (numNumbers == 0 || numNumbers == 1) {
            //
        } else {
            for (int i = 1; i < numNumbers; i++) {
                System.out.print(numbers.get(i) - numbers.get(i - 1) + ",");
            }
        }

}

def diff(inp):
	op=[]
	for i in range(0,len(inp)-1):
		op.append(abs(inp[i]-inp[i+1]))

	print(op)

inp = [787668, 787787, 787948, 787980, 788094, 788124]
diff(inp)

private static int[] diff(int[] a) {
        int[] output = new int[a.length - 1];
        for (int i = 1; i <= a.length - 1; i++) {
            int temp = a[i] - a[i - 1];
            if (temp < 0)
                temp*=-1;
            output[i - 1] = temp;
        }
        return output;

}

public static void Main()
	{
		int [] arr = {50,100,145,555,344,200};
		
		int nextSum = 0;
		
		for (int i = 0; i < arr.Length; i++)
		{
			nextSum += arr[i];
			
			if (i > 1)
			{
				nextSum -= arr[i-2];	
			}
			
			Console.WriteLine(nextSum);
				
		}
		
		
		
	}