import java.util.Random;

public class benchmark{
    public static void main(String[] args) {
        Random r = new Random();
        int fileSize = 200*1024*1024;
        fileSize += 11;
        String stringToFind = "hello world";
        char[] strArr = stringToFind.toCharArray();
        char[] data = new char[fileSize];
        for(int i = 0; i < fileSize; i++) {
            data[i] = (char) r.nextInt();
        }

        for(int i = fileSize - strArr.length; i < fileSize; i++) {
            data[i] = strArr[strArr.length - (fileSize - i)];
        }

        System.out.println(data[fileSize - 1]);
        long start = System.currentTimeMillis();

        int found = 0;
        for(int i = 0; i < fileSize; i++) {
            if (data[i] == strArr[found]) {
                found += 1;
            } else {
                found = 0;
            }

            if (found == strArr.length - 1) {
                System.out.println("Found at idx " + (i - strArr.length));
                found = 0;
            }

        }
        long end = System.currentTimeMillis();
        System.out.println("time was " + (end - start) / 1000.0 + " seconds.");


    }
}