c# - Dynamically Writing to a List -

so trying solve problem:

you given number n , 2*n numbers. write program check whether sum of odd numbers equal sum of n numbers. first number considered odd, next even, next odd again, etc. print result “yes” or “no”. in case of yes, print sum. in case of no, print difference between odd , sums.

input

the input data should read console.

• first line holds integer n – count of numbers.

• each of next 2*n lines holds 1 number.

the input data valid , in format described. there no need check explicitly.

output

• output must printed on console.

• print “yes, sum=s” s sum of odd n numbers in case of sum of odd n numbers equal sum of n numbers.

• otherwise print “no, diff=d” d difference between sum of odd n numbers , sum of n numbers. d should positive number. constraints

• number n integer in range [0...500].

• other numbers integers in range [-500 000 ... 500 000].

• allowed working time program: 0.25 seconds.

• allowed memory: 16 mb."

and current code, compiles this:

using system; using system.collections.generic; using system.linq; using system.text; using system.threading.tasks;  namespace odd_and_even_sum {     class program     {         static void main(string[] args)         {             int n = int.parse(console.readline());             list<string> stringofnumbers = new list<string>(2*n);             stringofnumbers.defaultifempty();             list<int> listofevennumbers = new list<int>(2*n);             list<int> listofoddnumbers = new list<int>(2*n);             int diff = 0;             (int = 0; < 2*n; i++)             {                 stringofnumbers[i] = console.readline();             }             list<int> listofnumber = new list<int>() { 1, 2, 3 };             (int = 0; < 2*n; i++)             {                 listofnumber[i] = int.parse(stringofnumbers[i]);             }             foreach (var item in listofnumber)             {                 if (iseven(item))                 {                     listofevennumbers.add(item);                 }                 else                 {                     listofoddnumbers.add(item);                 }             }             int sumofeven = listofevennumbers.sum();             int sumofodd = listofoddnumbers.sum();             if (sumofeven > sumofodd){                 diff = sumofeven - sumofodd;             }             if (sumofeven < sumofodd){                 diff = sumofodd - sumofeven;             }             if (sumofeven == sumofodd)             {                 console.writeline("yes, sum ={0}", sumofeven);             }             else             {                 console.writeline("no, diff={0}", diff);             }         }         public static bool iseven(int n)         {             if (n % 2 == 0)             {                 return true;             }             else             {                 return false;             }         }     } } 

my code compiling, when insert input values errror:

unhandled exception: system.argumentoutofrangeexception: index out of range. must non-negative , less size of collection. parameter name: index @ system.throwhelper.throwargumentoutofrangeexception() @ system.collections.generic.list`1.set_item(int32 index, t value) @ odd_and_even_sum.program.main(string[] args) in c:\users\user1\documents\v isual studio 2013\projects\odd , sum\program.cs:line 21

when write

list<string> stringofnumbers = new list<string>(2*n); 

you creating new empty list have zero element have initial capacity bound of 2*n. means it reserves memory inserting 2*n elements not have any.

stringofnumbers[i] = console.readline(); 

here trying access elements of list cause exception because there no element in list. should instead use

stringofnumbers.add(console.readline());