Develop Reference

Array rotation TLE (Time Limit Exceeded)

I am really confused why my java code is not working it is giving TLE on Code Monks on Hacker Earth.
Here is the link to the 1
Link to Question
the first question MONK AND ROTATION
import java.util.Scanner;
class TestClass {
static int[] ar=new int[100001];
public static void main(String args[] ){
Scanner in=new Scanner(System.in);
byte t=in.nextByte();
while(t-->0){
int n=in.nextInt();
int k=in.nextInt()%n;
for(int i=0;i<n-k;i++)
ar[i]=in.nextInt();
for(int i=0;i<k;i++)
System.out.print(in.nextInt()+" ");
for(int i=0;i<n-k;i++)
System.out.print(ar[i]+" ");
System.out.println();
}
}
}
I don't know why is it giving TLE I think there is some infinite loop going.
the question at the site is-
Monk and Rotation
Monk loves to perform different operations on arrays, and so being the principal of HackerEarth School, he assigned a task to his new student Mishki. Mishki will be provided with an integer array A of size N and an integer K , where she needs to rotate the array in the right direction by K steps and then print the resultant array. As she is new to the school, please help her to complete the task.
Input:
The first line will consists of one integer T denoting the number of test cases.
For each test case:
The first line consists of two integers N and K, N being the number of elements in the array and K denotes the number of steps of rotation.
The next line consists of N space separated integers , denoting the elements of the array A.
Output:
Print the required array.
Constraints:
1<=T<=20
1<=N<=10^5
0<=K<=10^6
0<=A[i]<=10^6
Sample Input
1
5 2
1 2 3 4 5
Sample Output
4 5 1 2 3
Explanation
Here T is 1, which means one test case.
denoting the number of elements in the array and , denoting the number of steps of rotations.
The initial array is:
In first rotation, 5 will come in the first position and all other elements will move to one position ahead from their current position. Now, the resultant array will be
In second rotation, 4 will come in the first position and all other elements will move to one position ahead from their current position. Now, the resultant array will be
Time Limit: 1.0 sec(s) for each input file
Memory Limit: 256 MB
Source Limit: 1024 KB

I'm not sure about the correctness of your solution, but try to use StreamTokenizer or BufferedReader instead of Scanner. Scanner is too slow and may result in TLE when you need to read a lot of data.

Reduce the number of reads and writes from/to System.in and System.out.
Look at the following solution
Scanner scanner = new Scanner(System.in);
int noOfTestCases = scanner.nextInt();
for (int i = 0; i < noOfTestCases; i++) {
int arraySize = scanner.nextInt();
int noOfRotations = scanner.nextInt();
noOfRotations = noOfRotations % arraySize;
scanner.nextLine();
String inputString = scanner.nextLine();
String[] inputStringArray = inputString.split(" ");
StringBuffer sb = new StringBuffer();
for (int j = 0; j < arraySize; j++) {
sb.append(inputStringArray[(arraySize + j - noOfRotations) % arraySize] + " ");
}
System.out.print(sb);
System.out.println("");
}

import java.util.*;
public class temp {
public static void main (String[] args) {
Scanner sc = new Scanner(System.in);
int t = sc.nextInt();
while(t-->0){
int n = sc.nextInt();
int k = sc.nextInt();
int p = 0;
int ar[] = new int[n];
for(int i=0;i<n;i++){
ar[i] = sc.nextInt();
}
k %= n;
for(int i=0;i<n;i++){
p = ar[(i+(n-k))%n];
System.out.print(p+" ");
}
System.out.println();
}
}
}
Though I have not used a big sized array in the starting, this code is working fine for all test cases.
Try this one.

Think from a different perspective. Instead of splitting the string and converting it into an array and applying the iterative logic, we can apply a different logic.
The trick is you just need to find the position of the input string where we have to split only once.
By that I mean,
input=>
6 2       //4 is the length of numbers and 2 is the index of rotation
1 2 3 4 5 6     //array (take input as a string using buffered reader)
Here, we just need to split the array string at the 2nd last space i.e. 4th space. So the output can be achieved by just splitting the string once-
5 6 1 2 3 4
first split- 5 6 + space + second split- 1 2 3 4
This logic worked for me and all the test cases passed.
Also don't forget to cover the corner case scenario when array input string is just one number.
Code Snippet-
int count=0;
for(int k=0; k<arr.length(); k++) {
if(arr.charAt(k)==' ')
count++;
if(count==size-rot) {
System.out.println(arr.substring(k+1,arr.length())
+ " " + arr.substring(0,k));
break;
}
}

Problem is in the System.out.print() call that is inside the for-loop. Thats a fairly heavy call and if called too many times and creates an overhead. This solution works:
//import for Scanner and other utility classes
import java.util.*;
class TestClass {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
String input = s.nextLine();
int noOfTests = Integer.parseInt(input);
for (int t = 0; t < noOfTests; t++) {
input = s.nextLine();
String[] str = input.split(" ");
int sizeOfArray = Integer.parseInt(str[0]);
int noOfRotations = Integer.parseInt(str[1]);
String strIntegerArray = s.nextLine();
String[] array = strIntegerArray.split(" ");
printRightRotatedArray(array, noOfRotations, strIntegerArray.length());
}
}
static void printRightRotatedArray(String[] array, int noOfRotations, int lengthOfStr) {
int len = array.length;
int noOfAcutalRotations = noOfRotations % len;
int startingIndex = len - noOfAcutalRotations;
StringBuilder sb = new StringBuilder(lengthOfStr+1);
for (int i = 0; i < len; i++) {
sb.append(array[(startingIndex + i) % len]);
sb.append(" ");
}
System.out.println(sb);
}
}

putting all into string buffer and print at the end worked for me.
class TestClass {
public static void main(String args[] ) throws Exception {
//BufferedReader
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int t = Integer.parseInt(br.readLine());
StringBuilder sb = new StringBuilder();// output
for(int i=0;i<t;i++){
String [] nk=br.readLine().split(" ");
int n= Integer.parseInt(nk[0]);
int k=Integer.parseInt(nk[1]);
String [] a=br.readLine().split(" ");
int split=n-(k%n);
for (int j = split; j < a.length; j++) {
sb.append(a[j]);
sb.append(' ');
}
for (int j = 0 ; j < split; j++) {
sb.append(a[j]);
sb.append(' ');
}
sb.append("\n");
}
System.out.println(sb);
}
}

Input inside Arrays (java)?

So, I have a very messy code. The purpose of the code is to find the minimum and maximum values of a set of numbers that the user entered using arrays. The problem is I don't know how to put the Array elements (Elements) into my array (numbersArray). Here's what I have so far :
package com.company;
import java.util.*;
import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
public class Main {
public static void main(String[] args) {
/* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
Scanner elements = new Scanner(System.in);
System.out.println("Enter in number of numbers:");
String num = elements.nextLine();
int numArrayElements = Integer.parseInt(num);
System.out.println("Enter in numbers please: ");
Scanner console = new Scanner(System.in);
String userInput = console.nextLine();
int Elements = Integer.parseInt(userInput);
int [] numbersArray = new int[numArrayElements];
int sum = 0;
for (int i = 0 ; i < numbersArray.length ; i++) {
int temp = numArrayElements.nextInt();
numbersArray[i] = temp;
sum += temp;
}
Arrays.sort(numbersArray);
System.out.println((sum - numbersArray[numbersArray.length-1])
+ " " + (sum - numbersArray[0]));
}
}
How can I make it so that I can put Elements into numbersArray?

Your major problem is the part where you try to read values entered by the user:
for (int i = 0 ; i < numbersArray.length ; i++) {
int temp = numArrayElements.nextInt();
...
}
The variable numArrayElements is of type int, you can't call a method nextInt on it, it does not exist.
The method, however, exists for objects of type Scanner, like your elements variable.
After that your code probably compiles and does something useful. At least you set the array items correctly by using
numbersArray[i] = temp;
I'm not that sure about the min/max part though. I don't get why you need the sum if you sort the array. After sorting you can just take the first (min) and last element (max) given by numbersArray[0] and numbersArray[numbersArray.length - 1].
And I'm not sure why you do the parsing stuff in between, does not seem necessary. Same holds for the second scanner, not needed since you already have one.
Let me show you a cleaner approach.
Scanner scanner = new Scanner(System.in);
// Amount of values
System.out.println("Enter amount of values:");
int amount = scanner.nextInt();
// Read values
System.out.println("Enter " + amount + " values:");
int[] values = new int[amount];
for (int i = 0; i < values.length; i++) {
values[i] = scanner.nextInt();
}
// Compute max and min
...
For the last part you have several options. The most efficient would probably be to remember it already at the moment where you read the values. Your sorting approach works too, but is much more work than needed since you don't need the order of all elements, you only need the min and max element.
Let's first do a manual approach
// Compute max and min
int max = Integer.MIN_VALUE;
int min = Integer.MAX_VALUE;
for (int value : values) {
if (value > max) {
max = value;
}
if (value < min) {
min = value;
}
}
The second approach uses a built-in method which essentially does the same. However, it is less efficient since we will first need to built a Collection on top of the array and then do two iterations instead of only one (one for max, one for min). Also, due to the conversion we need wrapper objects Integer instead of primitive values int.
// Compute max and min
Collection<Integer> valuesAsColl = Arrays.asList(values);
int max = Collections.max(valuesAsColl);
int min = Collections.min(valuesAsColl);
The third approach uses the Java Stream API (since Java 8), looks elegant and does not need to convert stuff to Integer or Collection. But the two iterations instead of one remain.
// Compute max and min
int max = Arrays.stream(values).max();
int min = Arrays.stream(values).min();

I not understand your ask .. however this code for set array size from user and numbers of array by user..
public class JavaApplication2 {
public static int[] numbers() {
Scanner element = new Scanner(System.in);
System.out.print("please insert array long : ");
int count = element.nextInt();
System.out.print("enter numers : ");
element.nextLine(); // throw away the newline.
int [] numbers = new int[count];
Scanner numScanner = new Scanner(element.nextLine());
for (int i = 0; i < count; i++) {
if (numScanner.hasNextInt()) {
numbers[i] = numScanner.nextInt();
} else {
System.out.println("You didn't provide enough numbers");
break;
}
}
return numbers;
}
public static void main(String[] args) {
int[] numbersa = numbers();
System.out.println(Arrays.toString(numbersa));
}
}

Inputing strings into an array

I'm a beginning programmer with the assignment to create a program that prompts the user to enter the number of elements that will then be stored into a String array. The second part of the assignment is to then list the array in ascending order. But I'm kind of stuck of the first part. If the user enters that there will be 3 elements after the 3rd string is entered I get an out of bounds exception. Below is the code.
import java.util.*;
public class arrays
{
public static void main(String[]arg)
{
Scanner input = new Scanner(System.in);
//Read user input.
System.out.print("How many Elements? ");
int num = input.nextInt();
String array[]= new String[num];
for (int i = 1 ; i <= num; i++ )
{
System.out.print("Enter element "+ i +": ");
array[i] = input.next();
}
System.out.println(array);
}
}

The array index starts at 0 so your loop should look like this:
for (int i = 0 ; i < num; i++ )
{
System.out.print("Enter element "+ (i+1) +": ");
array[i] = input.next();
}
Note that I also added +1 in the System.out.print to show "user friendly" output (e.g. "Enter element 1:" instead of "Enter element 0:" for the first element).
Another option would be to subtract 1 while accessing the array, which would allow you to keep the existing System.out.print line:
for (int i = 1 ; i <= num; i++ )
{
System.out.print("Enter element "+ i +": ");
array[i - 1] = input.next();
}
Although I feel that this is slightly less common practice.

Arrays in Java are numbered starting with zero, which means, your array of length 3 has this valid indices:
array[0]
array[1]
array[2]
I guess that's enough to send you on the right track ;-)

Start with i = 0 and go up to i < num, because in the example with three your array starts at 0 and goes up to 2, so it's no wonder that there's an out of bounds exception. That should fix the error.

you get the error because array index starts with 0. You should change your loop into this:
for (int i = 0 ; i < num; i++ )

change to array[i-1] = input.next();

Adding to an int inside an array

I keep trying to add (many times) +1 to a number (the number is zero) already in an array which is zero but it is not working.
int i=0;//var for arrays
int [] countArray = new int[10];
/////////////////////
//__________ ask for values --------------
System.out.println("Hello please enter the number you would" +
" like to be sorted separated by commas. \n" +
"Example: \" 2,3,5,83,2 \".\t only use" +
" commas. to separate numbers\n");
//----------- save values -----
Scanner scan = new Scanner(System.in);
String allInput = scan.nextLine();//single string object with all input
String [] arr = allInput.split(",");//string array that holds all values
//as String
int [] numbersArray =new int[arr.length] ;//numbers
for ( String w: arr){//change Strings to Int
numbersArray[i]= Integer.valueOf(arr[i]);
i++;
}
//__ set all number in count to zero because necessary
i=0;
for ( int x: countArray){//set all numbers to zero
countArray[i]=0;
i++;
} //everything zeroed
i=0;
This works now, thank you guys:
for (int x = 0; x < numbersArray.length; x++){
if (numbersArray[x] >=10 && numbersArray[x] <=100) {
countArray[(numbersArray[x]-1)/10]++;}
else{
if (numbersArray[x] >=0 && numbersArray[x] <=10)
{
countArray[1 -1]++;}
}
}

Instead of using a for-each loop to edit all the values, try to iterate through them using a standard for loop. Here is a shorthand version of what you wrote. Try this:
for (int x = 0; x < numbersArray.length; x++){
countArray[(numbersArray[x]-1)/10]++;
}

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException:

So my assignment is write a recursive Java method that finds the maximum of an array of
integers without using any loops. The input is a first line that contains a single integer n < 10. The next line contains n numbers separated by spaces. The output should be a single integer. Call your program FindMax. The below code is what I have so far, it compiles but instead of me being able to enter
input line 1: 5 (n) }
This is what I need to be able to input
input line2: 2 3 4 5 3 }
it makes me enter
input: 5 (n)
input: 2
input: 3
input: 4
input: 5
input: 3
also after entering the above I get:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 5
at FindMaxtesting.getmax(FindMaxtesting.java:35)
at FindMaxtesting.getmax(FindMaxtesting.java:48)
at FindMaxtesting.getmax(FindMaxtesting.java:42)
at FindMaxtesting.getmax(FindMaxtesting.java:42)
at FindMaxtesting.getmax(FindMaxtesting.java:42)
at FindMaxtesting.getmax(FindMaxtesting.java:42)
at FindMaxtesting.main(FindMaxtesting.java:17)
This is my code so far:
import java.util.Scanner;
public class FindMaxtesting
{
public static void main (String[]args)
{
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int i = 0;
int fin = 0;
System.out.println(getmax( Inca(n ) , n , fin , i));
}
public static int[] Inca(int n )
{
Scanner sc = new Scanner(System.in);
int[] arr = new int[n];
for(int j=0;j<n;++j)
{
arr[j] = sc.nextInt();
}
return arr;
}
public static int getmax ( int arr[], int n, int fin, int i )
{
int temp = 0;
if (fin < arr[i])
{
temp = fin;
fin = arr[i];
arr[i] = temp;
i++;
getmax(arr , n , fin , i);
}
else if (fin > arr[i])
{
i++;
getmax(arr , n , fin , i);
}
else if ( i == n-1 )
{
return fin;
}
return fin;
}
}

The essence of your problem is that in getmax you need to add the lines
if (i >= n)
return fin;
You are searching through the array recursively, which isn't really the best way to do it, but I assume that this is a homework problem, and you need to say when to stop looking further through the array, however you continue to look further in the array. When i>=n then you know you have searched the entire array, and can just return fin, as there are no further values that can be greater.