THIS PROBLEM WAS TAKEN FROM THE SEMIFINALS OF THE TOPCODER INVITATIONAL
TOURNAMENT
PROBLEM STATEMENT
Create a class LongCalc that will perform arithmetic operations on two whole
numbers, represented by Strings. The operation to be performed is indicated by
op, which will be 1 for addition, 2 for subtraction, 3 for multiplication, and
4 for integer division. The value returned from this operation will be a
numeric value held in a String (which may begin with a negative sign if
necessary).
DEFINITION
Class Name: LongCalc
Method Name: process
Parameters: String, String, int
Returns: String
Method signature (be sure your method is public): String process(String a,
String b, int op);
The operation that will be performed is <a op b>.
TopCoder will ensure the validity of the inputs. Inputs are valid if all of
the following criteria are met:
 Both a and b will consist of only digits, and that the first digit of each
number is greater than 0.
 Both a and b will have length between 1 and 50, inclusive.
 op will be either 1, 2, 3, or 4
JAVA NOTE
java.math.* will not be allowed
EXAMPLES
process("100", "50", 1) > "150"
process("100000000000000000000000000000000",
"400000000000000000000000000000000", 1) > "500000000000000000000000000000000"
process("3", "4", 2) > "1"
process("29", "465", 3) > "13485"
process("15", "2", 4) > "7"
