I tried for every possible words and numbers of words in the file and ALWAYS it gives the correct result. :(
package com.codegym.task.task22.task2207;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.*;
public class Solution {
public static List<Pair> result = new LinkedList<>();
public static void main(String[] args) throws IOException {
List<String> listOfWords = new ArrayList<>();
Map<String,String> mapa = new LinkedHashMap <>();
Scanner scanner = new Scanner(System.in);
String fileName = scanner.nextLine();
scanner.close();
BufferedReader bufferedReader = new BufferedReader(new FileReader(fileName));
String line = "";
while ((line = bufferedReader.readLine())!= null){
String[]tab = line.split(" ");
listOfWords.addAll(Arrays.asList(tab));
}
bufferedReader.close();
for (int i = 0; i < listOfWords.size()-1; i++) {
String word = listOfWords.get(i);
for (int j = i+1; j < listOfWords.size(); j++) {
StringBuilder stringBuilder = new StringBuilder(listOfWords.get(j));
String reversedWord = stringBuilder.reverse().toString();
if (word.equals(reversedWord))
mapa.put(word,listOfWords.get(j));
}
}
for (Map.Entry<String,String> element: mapa.entrySet()){
String key = element.getKey();
String value = element.getValue();
Pair pair = new Pair();
pair.first = key;
pair.second = value;
result.add(pair);
}
}
public static class Pair {
String first;
String second;
public Pair() {
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Pair pair = (Pair) o;
if (first != null ? !first.equals(pair.first) : pair.first != null) return false;
return second != null ? second.equals(pair.second) : pair.second == null;
}
@Override
public int hashCode() {
int result = first != null ? first.hashCode() : 0;
result = 31 * result + (second != null ? second.hashCode() : 0);
return result;
}
@Override
public String toString() {
return first == null && second == null ? "" :
first == null ? second :
second == null ? first :
first.compareTo(second) < 0 ? first + " " + second : second + " " + first;
}
}
}