Project Euler – Problem 2


Find the sum of all the even-valued terms in the Fibonacci sequence which do not exceed four million.

Problem:
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, …

Find the sum of all the even-valued terms in the sequence which do not exceed four million.

My Solution:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Euler
{
    class Problem2 : IProblemBase
    {
        //Each new term in the Fibonacci sequence is generated by adding the previous two terms.
        //By starting with 1 and 2, the first 10 terms will be:

        //1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

        //Find the sum of all the even-valued terms in the sequence which do not exceed four million.

        public Problem2()
        {
        }

        public string GetAnswer()
        {
            int result = 2;
            int runningTotal = 0;
            int sequenceOne = 1;
            int sequenceTwo = 2;
            while (sequenceTwo <= 4000000)
            {
                runningTotal = (sequenceOne + sequenceTwo);
                sequenceOne = sequenceTwo;
                sequenceTwo = runningTotal;
                if (sequenceTwo % 2 == 0)
                {
                    result += sequenceTwo;
                }

            }

            return result.ToString();
        }
    }
}
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