import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;

public class Library {

    public static String[] getPermutations(String s){
        StringBuilder sb = new StringBuilder();
        boolean[] used = new boolean[s.length()];
        ArrayList<String> list = getPerms(s, 0, used, sb, new ArrayList<String>());
        return list.toArray(new String[list.size()]);
    }

    private static ArrayList<String> getPerms(String input, int pos, boolean[] used, StringBuilder sb, ArrayList<String> list){
        if (pos == input.length()){
            list.add(sb.toString());
            return list;
        }
        for (int i = 0; i < input.length(); i++){
            //If the character has already been used, don't append it.
            if (used[i])    continue;

            used[i] = true;
            sb.append(input.charAt(i)); //append char to string builder
            getPerms(input, pos + 1, used, sb, list); //recursive call
            sb.setLength(sb.toString().length() - 1); //remove last char
            used[i] = false;
        }
        return list;
    }

    public static void printArray(int[][] array){
        for(int i = 0; i < array.length; i++){
            for(int j = 0; j < array[i].length; j++){
                System.out.print(array[i][j] + "  ");
            }
            System.out.println();
        }
    }

    public static void printArray(Object[] array){
        for(Object o : array)   System.out.println(array[0] instanceof String ? o : o.toString());
    }

    public static void printArray(int[] array){
        for(int i : array)  System.out.println(i);
    }

    public static void printArray(String[] array){
        for(String s : array)   System.out.println(s);
    }

    /**
     * @return sum of all values in array
     */
    public static int getSum(int[] array){
        int sum = 0;
        for(int i : array)  sum += i;
        return sum;
    }

    public static int[] shuffle(int[] n){
        int j, t;
        for(int i = n.length-1; i > 0; i--){
            j = (int) (Math.random()*i)+1;
            t = n[i];
            n[i] = n[j];
            n[j] = t;
        }
        return n;
    }

    /**
     * - Bubble Sort -
     */
    public static int[] sort(int[] values){
        int j = 0;
        boolean flag = true;
        while(flag){
            flag = false;
            for(int i = 0; i < values.length-1; i++){
                if(values[i] < values[i+1]){
                    j = values[i];
                    values[i] = values[i+1];
                    values[i+1] = j;
                    flag = true;
                }
            }
        }
        return values;
    }

    public static String[] sortByLength(String[] s){
        String j = "";
        boolean flag = true;
        while(flag){
            flag = false;
            for(int i = 0; i < s.length-1; i++){
                if(s[i].length() < s[i+1].length()){
                    j = s[i];
                    s[i] = s[i+1];
                    s[i+1] = j;
                    flag = true;
                }
            }
        }
        return s;
    }

    public static String[] toStringArray(ArrayList<String> s){
        return s.toArray(new String[s.size()]);
    }


    /**
     * @return True if the parameter is an integer
     */
    public boolean isNumber(String s){
        try{
            Integer.parseInt(s);
            return true;
        } catch(Exception e){
            return false;
        }
    }

    /**
     * @return true if the parameter is a consonant
     */
    public static boolean isConsonant(char c) throws Exception{
        if(Character.isAlphabetic(c)){
            return !isVowel(c);
        } else{
            throw new Exception("Parameter is not alphabetic");
        }
    }

    /**
     * @return true if the parameter is a vowel
     */
    public static boolean isVowel(char c) throws Exception{
        if(Character.isAlphabetic(c)){
            return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u';
        } else{
            throw new Exception("Parameter is not alphabetic");
        }
    }

    /**
     * @param the upper limit of the list of prime numbers
     */
    public static boolean[] getPrimes(int limit){
        boolean[] isPrime = new boolean[limit + 1];
        for (int i = 2; i <= limit; i++) {
            isPrime[i] = true;
        }

        for (int i = 2; i*i <= limit; i++) {
            if (isPrime[i]) {
                for (int j = i; i*j <= limit; j++) {
                    isPrime[i*j] = false;
                }
            }
        }
        return isPrime;
    }

    public static boolean isPrime(int n){
        return n >= Integer.MAX_VALUE ? false : getPrimes(n)[n];
    }


    public static String[] readFromFile(String filename){
        ArrayList<String> t = new ArrayList<String>();
        try{
            BufferedReader buffRead = new BufferedReader(new FileReader(new File(filename.endsWith(".txt") ? filename : filename + ".txt")));
            String line = buffRead.readLine();
            while(line != null){
                t.add(line);
                line = buffRead.readLine();
            }
            buffRead.close();
        } catch(IOException e){
            e.printStackTrace();
        }
        return t.toArray(new String[t.size()]);
    }
}