learn/AnagramSearch.java at master · IDeserve/learn · GitHub

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package questions.virendra;

import java.util.HashMap;
import java.util.HashSet;

public class AnagramSearch {

	public static boolean foundAnagram(HashMap<Integer,Integer> patternHash, HashMap<Integer,Integer>  textHash)
	{
		for(Integer key: patternHash.keySet())
		{
			if(textHash.containsKey(key))
			{
				if(textHash.get(key) != patternHash.get(key))
					return false;
			}
			else return false;
		}

		return true;
	}

	public static boolean anagramSubstringSearch(String pattern, String text)
	{
		HashMap<Integer,Integer> patternHash = new HashMap<Integer,Integer>();
		HashMap<Integer,Integer>  textHash    = new HashMap<Integer,Integer>();

		for(int i=0; i<pattern.length();i++)
		{
			int patCh = (int)pattern.charAt(i);
			int txtCh = (int)text.charAt(i);
			if(!patternHash.containsKey(patCh))
			{
				patternHash.put(patCh, 1);
			}
			else
			{
				int temp = patternHash.get(patCh);
				patternHash.put(patCh, ++temp);
			}

			if(!textHash.containsKey(txtCh))
			{
				textHash.put(txtCh, 1);
			}
			else
			{
				int temp = textHash.get(txtCh);
				textHash.put(txtCh, ++temp);
			}

		}


		int windowStart = 0;
		int windowEnd = pattern.length()-1;

		while(true)
		{
			if(foundAnagram(patternHash,  textHash))
			{
				return true;
			}
			windowStart++;
			windowEnd++;
			if(windowEnd >= text.length())
				return false;


			int txtCh = (int)text.charAt(windowStart -1);
			if(textHash.containsKey(txtCh))
			{
				int count = textHash.get(txtCh);
				if(count==1)
					textHash.remove(txtCh);
				else
					textHash.put(txtCh, count-1);
			}

			txtCh = (int)text.charAt(windowEnd);
			if(!textHash.containsKey(txtCh))
			{
				textHash.put(txtCh, 1);
			}
			else
			{
				int temp = textHash.get(txtCh);
				textHash.put(txtCh, ++temp);
			}

		}
	}


	public static void main(String args[])
	{
		AnagramSearch object = new AnagramSearch();

	 System.out.println(anagramSubstringSearch("xyiz", "afdgzyxksldfm"));

	}

}