LongestWith2DistinctCharacters.java

/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		
		System.out.println("Ans" +lengthOfLongestSubstringTwoDistinct("eceba") );
		System.out.println("Ans" +lengthOfLongestSubstringTwoDistinct("ecebaba") );


	}
	
	
static int lengthOfLongestSubstringTwoDistinct(String s) {
	int end = 0, begin = 0;
	Map<Character, Integer> map  = new HashMap<>();
	int maxLen = 0; 
	int counter = 0;
	while(end < s.length()) {
		char curr = s.charAt(end);
		if(!map.containsKey(curr)) {
			map.put(curr,1);
			counter++;
		} else {
			map.put(curr,map.get(curr)+1); 
		}
		end++;
		while(counter > 2) {
			char bChar = s.charAt(begin);
			map.put(bChar, map.get(bChar) -1);
			begin++;
			if(map.get(bChar) == 0){
				counter--;
			}
			
		}
		if(end - begin > maxLen) {
	 		maxLen = end -begin; 
	 		System.out.println(s.substring(begin,end));
		}

	}
	return maxLen;
		
}

}