Leetcode 383 Ransom Note

Given  an  arbitrary  ransom  note  string  and  another  string  containing  letters from  all  the  magazines,  write  a  function  that  will  return  true  if  the  ransom   note  can  be  constructed  from  the  magazines ;  otherwise,  it  will  return  false.   

Each  letter  in  the  magazine  string  can  only  be  used  once  in  your  ransom  note.

Note:
You may assume that both strings contain only lowercase letters.

canConstruct("a", "b") -> false
canConstruct("aa", "ab") -> false
canConstruct("aa", "aab") -> true

Solution:

hashtable:asdf

 public bool CanConstruct(string ransomNote, string magazine) {
        int magLength = magazine.Length;
        int ranLength = ransomNote.Length;

        if(ranLength>magLength) return false;
        if(ranLength==0) return true;
        Hashtable hashtable = new Hashtable();
        
        for(int j = 0; j< ranLength;j++)
        {
            if(hashtable.ContainsKey(ransomNote[j]))
            {
                int temp = (int)hashtable[ransomNote[j]];
                temp++;
                hashtable[ransomNote[j]] = temp;
            }
            else
            {
                hashtable.Add(ransomNote[j],1);
            }
        }
        
        for(int i= 0; i< magLength;i++)
        {
            if(hashtable.ContainsKey(magazine[i]))
            {
                int temp = (int)hashtable[magazine[i]];
                if(--temp <=0)  hashtable.Remove(magazine[i]);
                else hashtable[magazine[i]] = temp;
            }
            if(hashtable.Count==0) return true;
        }
        
        
        return false;
    }

2 pointer & sorting

public bool CanConstruct(string ransomNote, string magazine) {
        int magLength = magazine.Length;
        int ranLength = ransomNote.Length;

        if(ranLength>magLength) return false;
        if(ranLength==0) return true;
        
        var charR = ransomNote.ToCharArray();
        var charM = magazine.ToCharArray();
        Array.Sort(charR);
        Array.Sort(charM);
        int i = 0;
        int j = 0;
        while(j<magLength && i< ranLength)
        {
            if(charR[i] == charM[j])
            {
                i++;
                j++;
            }
            else if(charR[i] < charM[j])
            {
               return false;
            }
            else j++;
        }
        return (i== ranLength);
 
    }