problem involving matrix & binary search tree

Question

Hi,i am a new guy on this forum.I have only recently
taken to C# programming and facing a few problems.I hope
to get some help here and get to know some people.
My present problem looks like this:-
I have a 5x5 Matrix. Each cell consists a string value
ex: URL of any website.
I want to find out which string value occurs( i.e.
repeats ) maximum no. of times in the matrix.
I have a hint that BINARY SEARCH TREE will be used here
and that NODE class in c# may be used to implement
trees.
The output can be in the form of array/matrix/Binary
Search Tree etc.
I am not allowed to use unsafe block to create/access
trees.

Matthew Cochran · Answer

A binary search tree seems like a pretty sophisticated data structure to use to solve this problem when it can be done with some simple iterations.
For example:
given the following 5X5 matrix
String [][] matrix = new String [][]
{
new String []{ "A" , "B" , "C" , "D" , "E" },
new String []{ "F" , "G" , "H" , "I" , "J" },
new String []{ "A" , "B" , "C" , "C" , "D" },
new String []{ "F" , "G" , "H" , "H" , "H" },
new String []{ "A" , "B" , "H" , "D" , "E" }
};
----------------------- ----------------------- -----------------------
You'll have to visit each "cell" whatever solution you go with, so why not use a dictionary to count all occurances like this:
Dictionary String , Int32 > counter = new Dictionary String , Int32 >();
// count the instances and put them in the dictionary
foreach ( String [] strArray in matrix)
foreach ( String str in strArray)
if (counter.ContainsKey(str)) // if it is there, increment the count
counter[str]++;
else
counter.Add(str, 1); // if it is not there, add it
----------------------- ----------------------- -----------------------
Then you have a couple options to get the string with the most instances.  One way is through a simple iterative comparison:
KeyValuePair String , Int32 > result = new KeyValuePair string , int >( "" , -1);
foreach ( KeyValuePair String , Int32 > kvp in counter)
{
if (result.Value
result = kvp;
}
Console .WriteLine(result.Key + ": " + result.Value);
----------------------- ----------------------- -----------------------
Your other option would be to use LINQ syntax:
// using LINQ: It is a convienient and concise
// syntax for querying collections
KeyValuePair String , Int32 > biggest =
( from x in counter.AsQueryable()
orderby x.Value descending
select x)
.First();
Console .WriteLine(biggest.Key + ": " + biggest.Value);
----------------------- ----------------------- -----------------------
Hope this helps
-Matt