Java String Hashing: Sorting Sub-strings by Weight and Character Order

Question

Description:

problem name - String hasher

problem statement:

you are given a string and a number(sub-string length). the string consists of *,-, and + characters, and the string's length will be the multiple of the given number. Write a function to hash the string using the below hashing algorithm:

• split the given string into multiple sub-strings of a given length string from left
• calculate the weight of each sub-string. the number of times a unique sub-string value appears after splitting is defined as the weight of that sub-string -sort the unique sub-string values by weight in descending order. if 2 or more sub-strings have the same weight, then sort them by character order. * > - > + -create the hash by concatenating the sorted list of unique sub-strings and return the hash.

Example 1:

**input**: -+*++-*++-

sub-string length:2

**output**: *++--+

Explanation:

sub-string with length 2:

-+*++-*++-

unique sub-strings with weight

- -+ : 1
- *+ : 2
- +- : 2

• while sorting sub-strings by weight,*+ and +- sub-strings have same weight. i.e 2. so, we sort these sub-strings by character order resulting in *+ coming before +-.so,the final order is *++--+
• create the hash by concatenating the unique sub-string: *++--+

Sample Input

-+*++-*++-

2

sample output

*++--+

Java pseudo code to be built

import java.io.* ;
import java.util.* ;
import java.text.* ;
import java.math.* ;
import java.util.regrex.* ;

class Main{
public static void main ( String [] args) throws Exception {
StringBuilder inputData=new  StringBuilder() ;
String thisLine=null ;
BufferReader br= new  BufferReader (new InputStreamReader(System.in));
while((thisLine=br.readLine())!=null){
inputData.append(thisLine + "/n");
}
System.out.println(codeHere(inputData));
}

public static string codeHere(StringBuilder inputData){
// use this function to write your solution;
return inputData.toString();
}

my code :

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

class Main {
    public static void main(String[] args) throws Exception {
        StringBuilder inputData = new StringBuilder();
        String thisLine = null;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while ((thisLine = br.readLine()) != null) {
            inputData.append(thisLine + "\n");
        }
        System.out.println(codeHere(inputData));
    }

    public static String codeHere(StringBuilder inputData) {
        String[] lines = inputData.toString().split("\n");
        String inputString = lines[0].trim();
        int subStringLength = Integer.parseInt(lines[1].trim());

        return hashString(inputString, subStringLength);
    }

    public static String hashString(String inputString, int subStringLength) {
        Map<String, Integer> substringCount = new HashMap<>();
        for (int i = 0; i <= inputString.length() - subStringLength; i++) {
            String substring = inputString.substring(i, i + subStringLength);
            substringCount.put(substring, substringCount.getOrDefault(substring, 0) + 1);
        }

        List<String> uniqueSubstrings = new ArrayList<>(substringCount.keySet());
        uniqueSubstrings.sort((a, b) -> {
            int weightComparison = substringCount.get(b) - substringCount.get(a);
            if (weightComparison == 0) {
                return a.compareTo(b);
            }
            return weightComparison;
        });

        StringBuilder hash = new StringBuilder();
        for (String substring : uniqueSubstrings) {
            hash.append(substring);
        }

        return hash.toString();
    }
}

but it's not giving the expected output.

for input:

-+*++-*++-

2

output

*++++-+*-*-+

expected output

*++--+ 

Please Give easiest method if possible.