Project Euler #13 efficiency

Okay, so I finally tackled #13 from Project Euler. I'm said to announce it took me almost 2 hours to come up with this solution, after about an hour of thinking on how to do it.

Here's what I did:

```
private void Euler13()
{
// store 50 digit numbers into a 100 by 50 array
int[,] superMegaInt = { {3,7,1,0,7,2,8,7,5,3,3,9,0,2,1,0,2,7,9,8,7,9,7,9,9,8,2,2,0,8,3,7,5,9,0,2,4,6,5,1,0,1,3,5,7,4,0,2,5,0},
{4,6,3,7,6,9,3,7,6,7,7,4,9,0,0,0,9,7,1,2,6,4,8,1,2,4,8,9,6,9,7,0,0,7,8,0,5,0,4,1,7,0,1,8,2,6,0,5,3,8},
{7,4,3,2,4,9,8,6,1,9,9,5,2,4,7,4,1,0,5,9,4,7,4,2,3,3,3,0,9,5,1,3,0,5,8,1,2,3,7,2,6,6,1,7,3,0,9,6,2,9},
{9,1,9,4,2,2,1,3,3,6,3,5,7,4,1,6,1,5,7,2,5,2,2,4,3,0,5,6,3,3,0,1,8,1,1,0,7,2,4,0,6,1,5,4,9,0,8,2,5,0},
{2,3,0,6,7,5,8,8,2,0,7,5,3,9,3,4,6,1,7,1,1,7,1,9,8,0,3,1,0,4,2,1,0,4,7,5,1,3,7,7,8,0,6,3,2,4,6,6,7,6},
{8,9,2,6,1,6,7,0,6,9,6,6,2,3,6,3,3,8,2,0,1,3,6,3,7,8,4,1,8,3,8,3,6,8,4,1,7,8,7,3,4,3,6,1,7,2,6,7,5,7},
{2,8,1,1,2,8,7,9,8,1,2,8,4,9,9,7,9,4,0,8,0,6,5,4,8,1,9,3,1,5,9,2,6,2,1,6,9,1,2,7,5,8,8,9,8,3,2,7,3,8},
{4,4,2,7,4,2,2,8,9,1,7,4,3,2,5,2,0,3,2,1,9,2,3,5,8,9,4,2,2,8,7,6,7,9,6,4,8,7,6,7,0,2,7,2,1,8,9,3,1,8},
{4,7,4,5,1,4,4,5,7,3,6,0,0,1,3,0,6,4,3,9,0,9,1,1,6,7,2,1,6,8,5,6,8,4,4,5,8,8,7,1,1,6,0,3,1,5,3,2,7,6},
{7,0,3,8,6,4,8,6,1,0,5,8,4,3,0,2,5,4,3,9,9,3,9,6,1,9,8,2,8,9,1,7,5,9,3,6,6,5,6,8,6,7,5,7,9,3,4,9,5,1},
{6,2,1,7,6,4,5,7,1,4,1,8,5,6,5,6,0,6,2,9,5,0,2,1,5,7,2,2,3,1,9,6,5,8,6,7,5,5,0,7,9,3,2,4,1,9,3,3,3,1},
{6,4,9,0,6,3,5,2,4,6,2,7,4,1,9,0,4,9,2,9,1,0,1,4,3,2,4,4,5,8,1,3,8,2,2,6,6,3,3,4,7,9,4,4,7,5,8,1,7,8},
{9,2,5,7,5,8,6,7,7,1,8,3,3,7,2,1,7,6,6,1,9,6,3,7,5,1,5,9,0,5,7,9,2,3,9,7,2,8,2,4,5,5,9,8,8,3,8,4,0,7},

• Don't hard code the input. Instead, make your program read and parse a text file containing the input, or something like that.

• If you can use BigInteger to represent the numbers, use it. If you think that would be cheating, write your own BigInteger that supports Parse(), ToString() and +.

• You can then use LINQ to sum the numbers. Sum() doesn't work for BigIntegers, but you can use Aggregate().

With that, your code would look something like this:

string result =
    File.ReadAllLines("euler13.txt")
        .Select(BigInteger.Parse)
        .Aggregate((i1, i2) => i1 + i2)
        .ToString()
        .Substring(0, 10);

This is basically the same code as the one from Nakilon's comment, only in a language that supports names with more than 4 characters :-)

StackExchange Code Review Q#27931, answer score: 5