How can check anagram strings in C#

Question

Given two strings A and B, check if they are anagrams.

Two strings are said to be anagrams, if one string can be obtained by rearranging the letters of another.

Examples of anagrams are

• dog, god
• abac, baac
• 123, 312

abab, aaba and dab, baad are not anagrams.

INPUT :

First line of the input is the number of test cases T. It is followed by T lines, each line has two space separated strings A and B;

OUTPUT

For each test case, print "YES" if they are anagrams, otherwise print "NO". (without quotes)

Constraints

1. 1 <= T <= 10
2. A and B both contain only lower case latin letters 'a' to 'z' and digits 0 to 9.
3. Length of each string A and B does not exceed 5*10^5 (500000)

`

Sample Input            Sample Output
------------------------------------
3                           YES
abcd bcda                   NO
bad daa                     YES
a1b2c3 abc123               NO

How can we do this ?

bool anagramChecker(string first, string second)
{
    if(first.Length != second.Length)
        return false;

    if(first == second)
        return true;//or false: Don't know whether a string counts as an anagram of itself

    Dictionary<char, int> pool = new Dictionary<char, int>();
    foreach(char element in first.ToCharArray()) //fill the dictionary with that available chars and count them up
    {
        if(pool.ContainsKey(element))
            pool[element]++;
        else
            pool.Add(element, 1);
    }
    foreach(char element in second.ToCharArray()) //take them out again
    {
        if(!pool.ContainsKey(element)) //if a char isn't there at all; we're out
            return false;
        if(--pool[element] == 0) //if a count is less than zero after decrement; we're out
            pool.Remove(element);
    }
    return pool.Count == 0;
}

Answer 1

Is this your solution?

string a = "abcd";
string b = "bcda"; // bad daa a1b2c3 abc123

string aa = String.Concat(a.OrderBy(c => c));
string bb = String.Concat(b.OrderBy(c => c));

if (aa == bb)
{
     Console.WriteLine("YES");
}
else
{
     Console.WriteLine("NO");
}

or shorter

if (String.Concat(a.OrderBy(c => c)).Equals(String.Concat(b.OrderBy(c => c))) ...

Answer 2

There's the fast way and the simple way:

void Test()
{
    string a = "abccabccabccabccabccabccabccabccabccabccabccabccabccabccabccabcc";
    string b = "bcacbcacbcacbcacbcacbcacbcacbcacbcacbcacbcacbcacbcacbcacbcacbcac";

    IsAnagramSimple(a, b);
    IsAnagramFast(a, b);
}


private bool IsAnagramSimple(string a, string b)
{
    return a.OrderBy(c => c).SequenceEqual(b.OrderBy(c => c));
}

private bool IsAnagramFast(string a, string b)
{
    if (a.Length != b.Length)
    {
        return false;
    }

    var aFrequency = CalculateFrequency(a);
    var bFrequency = CalculateFrequency(b);

    foreach (var key in aFrequency.Keys)
    {
        if (!bFrequency.ContainsKey(key)) return false;
        if (aFrequency[key] != bFrequency[key]) return false;
    }

    return true;
}

private Dictionary<char, int> CalculateFrequency(string input)
{
    var frequency = new Dictionary<char, int>();
    foreach (var c in input)
    {
        if (!frequency.ContainsKey(c))
        {
            frequency.Add(c, 0);
        }
        ++frequency[c];
    }
    return frequency;
}

Answer 3

public bool IsAnagram(string s1,string s2)
{
  if (s1.Length != s2.Length)
     return false;
  var s1Array = s1.ToLower().ToCharArray();
  var s2Array = s2.ToLower().ToCharArray();

  Array.Sort(s1Array);
  Array.Sort(s2Array);

  s1 = new string(s1Array);
  s2 = new string(s2Array);

  return s1 == s2;
}