Develop Reference

How to split a String into an Array if a .contains() condition is met?

I'm doing a hackerrank medium challenge for a password cracker. I want to be able to check if a given string, attempt, contains all the words in pass. pass is an array of passwords and attempt is a concatenation of random entries in pass. If attempt contains ONLY words that are found as entries in pass, then it is deemed a good password and the words from the input of attempt, limited with spaces, is printed.
Sample Input
3 //3 attempts
6 //6 words for attempt 1
because can do must we what //pass[]
wedowhatwemustbecausewecan //attempt
2 //...
hello planet
helloworld
3
ab abcd cd
abcd
Expected Output
we do what we must because we can
WRONG PASSWORD //Because planet is not in pass[]
ab cd
Code
public class Solution {
static String passwordCracker(String[] pass, String attempt) {
int arrayLength=pass.length;
int accuracy=0;
String trips_array[] = new String[pass.length];
String [] newWord = new String[20];
for (int i=0; i<pass.length;i++)
{
// int j=0;
String[] arr = pass[i].split(" ");
//-------------------------------
if (attempt.contains(pass[i]))
{
accuracy++;
newWord[i] = pass[i];
trips_array[i] = attempt.split(" ");
}
//------------------------------
}
StringBuilder sb = new StringBuilder();
for (String words : trips_array) {
sb.append(words);
}
for (int i=0; i<pass.length;i++)
{
if (accuracy==pass.length)
return sb.toString() + " ";
else
return "WRONG PASSWORD";
}
return "test";
}
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int t = in.nextInt();
for(int a0 = 0; a0 < t; a0++){
int n = in.nextInt();
String[] pass = new String[n];
for(int pass_i = 0; pass_i < n; pass_i++){
pass[pass_i] = in.next();
}
String attempt = in.next();
String result = passwordCracker(pass, attempt);
System.out.println(result);
}
in.close();
}
}
The part in focus is the part in the //----------------- comment section. Basically, my goal is to see if the attempt contains the correct entries in pass, and if so, save that substring of the attempt (or similarly, the entry in pass) to a new array which can be printed in the correct order. If you check the expected output above, you'll see that the output is the same as attempt except with spaces.
Essentially, I would need to find the breaks in the words of attempt and print that if it fulfills the above requirements (first paragraph).
See this for more details
https://www.hackerrank.com/challenges/password-cracker/problem

If it helps you
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int testNumb = Integer.parseInt(reader.readLine());
List<String> passList = new ArrayList<>();
List<String> attList = new ArrayList<>();
for (int i = 0; i < testNumb; i++) {
reader.readLine();
passList.add(reader.readLine());
attList.add(reader.readLine());
}
reader.close();
for (int i = 0; i < testNumb; i++) {
String s1 = passList.get(i);
String s2 = attList.get(i);
StringBuilder sb = new StringBuilder();
String[] s1Arr = s1.split(" ");
while (s2.length() > 0) {
int s2Lenght = s2.length();
for (String s : s1Arr) {
if (s2.startsWith(s)) {
sb.append(s + " ");
s2 = s2.substring(s.length());
}
}
if (s2.length() == s2Lenght) {
sb = new StringBuilder("wrong pass");
break;
}
}
System.out.println(sb.toString());
}

Your for loop looks too complicated, here is how I would approach that part.
boolean isAllWords = true;
int checksum = 0;
for (int j = 0; j < pass.length; j++) {
if (!attempt.contains(pass[j]) {
isAllWords = true;
break;
}
checksum += pass[j].length;
}
if (isAllWords && checksum == attempt.length) {
//This means attempt contains all words in pass array and nothing more
//... handle successful attempt
} else {
//... handle bad attempt
}

Exception in thread "main" java.lang.NumberFormatException: For input string: "" for user input

Even though I have parsed it to an integer value I'm still getting an error. I need to get the integer value from a String input where I remove the comma and space, and store it in an array, then I convert that array to an integer array
import java.util.ArrayList;
import java.util.Scanner;
public class SeriesSolution {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int count = sc.nextInt();
ArrayList<Integer> modes = new ArrayList<>();
for (int x = 0; x < count; x++) {
String lines = sc.nextLine();
String[] strs = lines.split(", ");
int[] array = new int[strs.length];
for (int i = 0; i < strs.length; i++) {
if (Integer.parseInt(strs[i]) > 0 && Integer.parseInt(strs[i]) < 100) {
array[i] = Integer.parseInt(strs[i]);
}
}
modes.add(mode(array));
}
for (int y:modes){
System.out.println(y);
}
}
private static int mode(int a[]) {
int maxValue=0, maxCount=0;
for (int anA : a) {
int count = 0;
for (int anA1 : a) {
if (anA1 == anA) ++count;
}
if (count > maxCount) {
maxCount = count;
maxValue = anA;
}
}
return maxValue;
}
}

The issue is mainly because Scanner accepts Enter keystroke as input. And because of which
String lines = sc.nextLine();
this peice of code stores an empty string into lines variable. This empty string throws NumberFormatException when passed to parseInt()
I would recommend you to use BufferedReader with InputStreamReader
BufferedReader br = new BuffereedReader(new InputStreamReader(System.in));
This is good for larger inputs and is error free. Though empty checks are must as prevention is better.
If you want to use Scanner, I would recommend you to update the code and use the below snippet of code.
String lines = "";
while (lines.equals("")) {
lines = sc.nextLine();
}

Do a check before the parseInt
if (strs[i] != null && !"".equals(strs[i]) && Integer.parseInt(strs[i]) ...
Or surround it with a try catch to catch the NumberformatException that will happen if a string is inserted instead of a number

System.out.print() not printing to terminal

This may be a very stupid question but I am trying to modify provided code from Sedgewick's "Algorithms" textbook for a class project. For debugging purposes I just want to print out some information to terminal at various points. Not matter where I insert System.out.println("testing") for example, I recieve no errors and the program runs to completion but nothing was ever printed out. Is it possible that the target destination for printing is not terminal for some reason?
public class LZW {
private static final int R = 256; // number of input chars
private static final int L = 4096; // number of codewords = 2^W
private static final int W = 12; // codeword width
public static void compress() {
String input = BinaryStdIn.readString();
TST<Integer> st = new TST<Integer>();
for (int i = 0; i < R; i++)
st.put("" + (char) i, i);
int code = R+1; // R is codeword for EOF
while (input.length() > 0) {
String s = st.longestPrefixOf(input); // Find max prefix match s.
BinaryStdOut.write(st.get(s), W); // Print s's encoding.
int t = s.length();
if (t < input.length() && code < L) // Add s to symbol table.
st.put(input.substring(0, t + 1), code++);
input = input.substring(t); // Scan past s in input.
}
BinaryStdOut.write(R, W);
BinaryStdOut.close();
}
public static void expand() {
String[] st = new String[L];
int i; // next available codeword value
// initialize symbol table with all 1-character strings
for (i = 0; i < R; i++)
st[i] = "" + (char) i;
st[i++] = ""; // (unused) lookahead for EOF
int codeword = BinaryStdIn.readInt(W);
if (codeword == R) return; // expanded message is empty string
String val = st[codeword];
while (true) {
BinaryStdOut.write(val);
codeword = BinaryStdIn.readInt(W);
if (codeword == R) break;
String s = st[codeword];
if (i == codeword) s = val + val.charAt(0); // special case hack
if (i < L) st[i++] = val + s.charAt(0);
val = s;
}
BinaryStdOut.close();
}
public static void main(String[] args) {
System.out.println("Testing123");
if (args[0].equals("-")) compress();
else if (args[0].equals("+")) expand();
else throw new IllegalArgumentException("Illegal command line argument");
}
}

Trouble trying to find a word in a String array

For the code, it wakes a user input and splits it by witespaces then takes the individual words from the user input and checks to see if the singular word is in the text file( containing parallel arrays with one being a string array and the other an int array). For every time it finds the user inputted word it needs to add one but the problem is that I don't know how to implement either match, or compare or equalsTo to check to see if the word is in the String array.
public class MovieReviewSentimentAnalysis {
static Scanner userInput = new Scanner(System.in);
public static void main(String[] args) {
// TODO: complete me
//make own arrays to pass by value
//movieReviewComments = the text
String[] movieReviewComments = new String[10000];
//movieReviewScores = numeric values, avoid lit. values
int[] movieReviewScores = new int[10000];
String userComment = "";
// String reviewFile = "";
// reviewFile = args[0];
String whiteComment = "";
MovieReviewReader.readMovieReviews("movie_reviews.txt", movieReviewComments, movieReviewScores); //string, string array, and int array
System.out.println("Please type one line of review and when you are done press either Ctr D or Ctr Z");
userComment = userInput.nextLine();
System.out.println(userComment);
String[] words2 = userComment.split("[\\W]");
double itemCount = 0;
double wordTotal = 0;
double totalSumOfUserCommentWords = 0;
String test = "";
// int itemCount = words.length;
for (int i = 0; i < words2.length; i++)
{
test = words2[i];
itemCount = wordCount(test, movieReviewComments, movieReviewScores);
wordTotal += itemCount;
totalSumOfUserCommentWords = wordTotal / userComment.length();
// System.out.println(totalSumOfUserCommentWords);
}
// System.out.println(reviewFile);
System.out.println("Incomplete assignment");
userInput.close();
}
public static double wordCount(String test, String[] movieReviewComments, int[] movieReviewScores)
{
double storeScore = 0;
double totalSumofReviewScores = 0;
double numOfTimesWordAppears = 0;
for (int i=0; i < (movieReviewComments.length); i++)
{
if (test.equals(movieReviewComments[i])) //////////////////////////////////////////////////////////SOMETHING'S OFF
{
storeScore = movieReviewScores[i];
totalSumofReviewScores += storeScore;
numOfTimesWordAppears++;
System.out.println("Found"); //QUQ when will you appear!?!?
}
else
System.out.println("You dun goofed"); //delete after fixing problem
}
double wordScoreAverage = totalSumofReviewScores / numOfTimesWordAppears;
return wordScoreAverage;
}

It is very simple. You can do it the following way:
if (movieReviewComments[i].toLowerCase().contains(test.toLowerCase())
And if you want to test an equal comparison and not containment, use following instead:
if (test.equalsIgnoreCase(movieReviewComments[i])

Changing input so in can take any length of string, problems with output

Currently I have a method that asks user for an input string but only outputs the first 16 characters! The method is supposed to take in any length of string then output the characters in 4x4 blocks after it does the following: first row remains the same. Shift the second row one position to the left, then shifts the third row two positions to the left. Finally, shift the fourth row three positions to the left. As of now it will only output the first 4x4 block
Also I am not sure how I can change the method so it doesnt ask for user input
I would like it to use a given string like:
String text = shiftRows("WVOGJTXQHUHXICWYYMGHTRKQHQPWKYVGLPYSPWGOINTOFOPMO");
"WVOGJTXQHUHXICWYYMGHTRKQHQPWKYVGLPYSPWGOINTOFOPMO" is the given encrypted string I would like to use. but without asking for user input..I keep getting errors and incorrect outputs..please show how I might fix this
code I am using:
public class shiftRows {
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
String[] input= new String[4];
String[] output= new String[4];
System.out.println("Enter a String");
String inputStr = sc.next();
for (int i = 0, n = 0; i < 4; i++, n+=4) {
input[i] = inputStr.substring(0+n, 4+n);
}
// -
output[0] = input[0];
for(int i=1; i<4; i++)
{
output[i] = Shift(input[i],i);
}
for(int i=0; i<4; i++)
{
System.out.println(output[i]);
}
}
public static String Shift(String str, int shiftNum)
{
char[] out = new char[4];
if(shiftNum==1)
{
out[0]=str.charAt(1);
out[1]=str.charAt(2);
out[2]=str.charAt(3);
out[3]=str.charAt(0);
}
if(shiftNum==2)
{
out[0]=str.charAt(2);
out[1]=str.charAt(3);
out[2]=str.charAt(0);
out[3]=str.charAt(1);
}
if(shiftNum==3)
{
out[0]=str.charAt(3);
out[1]=str.charAt(0);
out[2]=str.charAt(1);
out[3]=str.charAt(2);
}
return new String(out);
}
}

Here's a good way to do it :
import java.util.Scanner;
public class shiftRows {
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
String inputStr = "WVOGJTXQHUHXICWYYMGHTRKQHQPWKYVGLPYSPWGOINTOFOPMO";
for (int i = 0 ; i < inputStr.length() ; i++){
System.out.print(inputStr.charAt(i));
if ((i + 1)%4 == 0) System.out.println();
}
}
}
If you want to stock it into a String, just concatenate at each loop and add a "\n" each time the if test is valid.