На всех тестовых файлах выводит правильное значение
package com.javarush.task.task19.task1907;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/*
Считаем слово
*/
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String fileName = reader.readLine();
reader.close();
FileReader fileReader = new FileReader(fileName);
StringBuilder builder = new StringBuilder();
while (fileReader.ready()) {
char c = (char) fileReader.read();
builder.append(c);
}
fileReader.close();
String fileString = builder.toString();
Pattern pattern = Pattern.compile("world");
Matcher matcher = pattern.matcher(fileString);
List<String> list = new ArrayList<>();
while (matcher.find()) {
int start = matcher.start();
int end = matcher.end();
list.add(fileString.substring(start, end));
}
System.out.println(list.size());
}
}