Input test cases/Boundary/Tricky

Find tricky/boundary/edge test cases for the problem below

Given a paragraph of text, write a program to find the first shortest sub-segment that contains each of the given k words at least once. A segment is said to be shorter than other if it contains less number of words.

Ignore characters other than [a-z][A-Z] in the text. Comparison between the strings should be case-insensitive.

If no sub-segment is found then the program should output “NO SUBSEGMENT FOUND”.

Input format :

First line of the input contains the text.
Next line contains k , the number of words given to be searched.
Each of the next k lines contains a word.

Output format :

Print first shortest sub-segment that contains given k words , ignore special characters, numbers.If no sub-segment is found it should return “NO SUBSEGMENT FOUND”

Sample Input :

This is a test. This is a programming test. This is a programming test in any language.

Sample Output :

a programming test This

Explanation :
In this test case segment “a programming test. This” contains given four words. You have to print without special characters, numbers so output is “a programming test This”. Another segment “This is a programming test.” also contains given four words but have more number of words.

Constraint :

Total number of character in a paragraph will not be more than 200,000.
0 < k <= no. of words in paragraph.
0 < Each word length < 15

2 cases where people mostly fail are limited input size for paragraph text…
and not giving duplicate strings(in the list of words to be found)

Forget about mixing special characters/spaces with alphabets to form a string(word) to be included in the list of words to be found(u can ignore this case)


I guess I’m hit with this tricky boundary case here! with the following code:
The code passes 9/10 TC in

But for one TC it’s crapping out. Any pointers?

public class Solution {

public static int getSubSeqEnd(Integer curr_begin, Integer prev_begin, Integer curr_min_len, ArrayList<Integer> input_int, ArrayList<Integer> key_int)
	//check if minimum no. words required are left in the string to scan
	if ((curr_begin + key_int.size() -1)  > input_int.size())
		return -1;
	//ensure curr_begin starts only from an index more than (prev_begin+curr_min_len) otherwise previous was the minimum subsegment
	if (curr_begin == (prev_begin+curr_min_len-1))
		return -1;
	HashMap<Integer, Integer> key_flags = new HashMap<>();
	for (int i=curr_begin; i<input_int.size(); i++)
		if ((i-curr_begin)>=curr_min_len)
			return -1;
		Integer curr_word = input_int.get(i);
		if (key_int.contains(curr_word) && key_flags.get(curr_word) == null)
			key_flags.put(curr_word, 1);
		if (key_flags.size() == key_int.size())
			return i;
	return -1;
public static void main(String[] args)  {
	String input = "";
	String[] key = null;
	Integer n_keys=0;
	//BufferedReader br = new BufferedReader(new InputStreamReader(;
	//input = br.readLine();
	Scanner sc = new Scanner(;
	input = sc.nextLine();
	if (input.length() > 200000)
	input = input.replaceAll("[^A-Za-z]+", "+").replaceAll("\\+", " ").trim();
	n_keys = sc.nextInt();//Integer.parseInt(br.readLine());
	key = new String[n_keys];
	for (int i=0;i<n_keys; i++)
		key[i] =;//br.readLine();
	catch (Exception ex)
		System.out.println("Total number of characters in a paragraph should not be more than 200,000.");
	ArrayList<Integer> input_int = new ArrayList<Integer>(); //integer array representation of input
	ArrayList<Integer> select_indices = new ArrayList<Integer>(); //possible start/end indices of the subsegment;
	//map representing key words and their mapped integer values
	HashMap<String, Integer> key_int = new HashMap<String, Integer>();
	for (int i=0; i<key.length; i++)
		String curr_key = key[i].toLowerCase();
		curr_key = key[i].replaceAll("[^a-zA-Z]", "");
		if(!key_int.containsKey(curr_key) && (curr_key.compareTo("") !=0) )
			key_int.put(curr_key, -1);//mark as not present by default
	//Scan input string assign an integer for every word:
	HashMap<String, Integer> wordmap = new HashMap<String, Integer>();
	String curr_word = "";
	Integer k=1;
	String[] input_parts = input.split(" ");
	String input_part_lower=null;
	for (int i=0;i<input_parts.length; i++)
		//Constraint check
		if (input_parts[i].length() >= 15)
		input_parts[i] = input_parts[i].replaceAll("[^a-zA-Z]", "");
		input_part_lower = input_parts[i].toLowerCase();
		if (!wordmap.containsKey(input_part_lower))
			wordmap.put(input_part_lower, k++);
		//Integer array representation of input
		//update key_int with the integer value of each words if it's not already updated
		if (key_int.containsKey(input_part_lower))
			//Update this as a possible start/end index of the subsegment
			if (key_int.get(input_part_lower) == -1)
				key_int.put(input_part_lower, wordmap.get(input_part_lower));
	//Constraints check
	if (n_keys < 1)
	//Error check if key is not in the Text, no point in proceeding.
	if (key_int.containsValue(-1))
		System.out.println("NO SUBSEGMENT FOUND");
	//Now start at select indices and go till the subsequence is found fully
	Integer min_begin=0, min_end=input_int.size()-1, curr_begin = -1, prev_begin=-1, curr_min_len = Integer.MAX_VALUE, possible_end=-1;
	ArrayList<Integer> key_int_arr  = new ArrayList<>();
	Iterator it = select_indices.iterator();
	while (it.hasNext())
		curr_begin = (Integer);
		possible_end = getSubSeqEnd(curr_begin, prev_begin, curr_min_len, input_int, key_int_arr);
		if (possible_end >= 0)
			curr_min_len = possible_end - curr_begin;
			min_begin = curr_begin;
			min_end = possible_end;	
		prev_begin = curr_begin;
	int n_words = min_end-min_begin + 1;
	int start_i = 0;
	for (int i=min_begin; i<=min_end; i++)
		if (i != min_end)
			System.out.print(" ");



Explain your approach.

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