package com.strings;

import java.util.HashMap;
import java.util.Map;

public class LongestSubstring {

	public int findLongestSubstringOf2Chars(String input) {
		Map<Character, Integer> map = new HashMap<Character, Integer>();
		int curr_start = 0, curr_window_size = 1;
		int max_start=0, max_window_size=1;
		if (input.length() <= 2) return input.length();

		for (int i = 0; i < input.length(); i++){
			char ch = input.charAt(i);
			if (map.containsKey(ch)){
				map.put(ch, map.get(ch) + 1);
			} else {
				map.put(ch, 1);
			}

			if (map.size() > 2){
				curr_window_size = Math.max(curr_window_size, i - curr_start);
				if (curr_window_size > max_window_size){
					max_start = curr_start;
					max_window_size = curr_window_size;
				}

				while (map.size() > 2){
					char temp = input.charAt(curr_start);
					int count = map.get(temp);
					if (count > 1) {
						map.put(temp, count - 1);
					} else {
						map.remove(temp);
					}
					curr_start++;
				}
			}
		}

		if (curr_window_size > max_window_size){
			System.out.println(input.substring(curr_start, curr_start + curr_window_size));
			return curr_window_size;
		} else {
			System.out.println(input.substring(max_start, max_start + max_window_size));
			return max_window_size;
		}


	}

	public static void main(String[] args) {
		LongestSubstring a = new LongestSubstring();
		String input1 = "aaabbbccccddee";
		String input2 = "abbcbcd";
		System.out.println(a.findLongestSubstringOf2Chars(input1));
		System.out.println(a.findLongestSubstringOf2Chars(input2));

	}

}