An integer array as a key for Dictionary

You can create an IEqualityComparer to define how the dictionary should compare items. If the ordering of items is relevant, then something like this should work:

public class MyEqualityComparer : IEqualityComparer<int[]>
{
    public bool Equals(int[] x, int[] y)
    {
        if (x.Length != y.Length)
        {
            return false;
        }
        for (int i = 0; i < x.Length; i++)
        {
            if (x[i] != y[i])
            {
                return false;
            }
        }
        return true;
    }

    public int GetHashCode(int[] obj)
    {
        int result = 17;
        for (int i = 0; i < obj.Length; i++)
        {
            unchecked
            {
                result = result * 23 + obj[i];
            }
        }
        return result;
    }
}

Then pass it in as you create the dictionary:

Dictionary<int[], string> dic
    = new Dictionary<int[], string>(new MyEqualityComparer());

Note: calculation of hash code obtained here: What is the best algorithm for an overridden System.Object.GetHashCode?

Maybe you should consider using a Tuple

var myDictionary = new Dictionary<Tuple<int,int>, string>(); 
myDictionary.Add(new Tuple<int,int>(3, 3), "haha1"); 
myDictionary.Add(new Tuple<int,int>(5, 5), "haha2"); 

According to MSDN , Tuple objects Equals method will use the values of the two Tuple objects