introduction to online judges

AUTOMATIC

EVALUATIONOF JAVA PROGRAM

THROUGH ONLINE JUDGE

TABLE OF CONTENTS

l What is an Online Judge?l l Difference between User-oriented

programs and Online Judge oriented programs

l l Why do we need Ojs?l l Practices to considerl l MOSS (Massive Online Software

Similarity)l

WHAT IS AN OJ? Online system

Compile and execute code

Test programs with pre-constructed data

Offline User Oriented Program

import java.io.*;public class Add{

public static void main(String args[])throws IOExeception{

int a, b, sum;BufferedReader br=new

BufferedReader(new InputStreamReader(System.in));

System.out.println(“Enter first number:”);

a=Integer.parseInt(br.readLine());System.out.println(“Enter

second number:”);

b=Integer.parseInt(br.readLine());sum=a+b;

System.out.println(“Sum=“ +sum);}}

Online Judge Oriented Program

import java.io.*;public class Add{

public static void main(String args[])throws IOExeception{

int a, b, sum;BufferedReader br=new

BufferedReader(new InputStreamReader(System.in));a=Integer.parseInt(br.readLine()); b=Integer.parseInt(br.readLine());

sum=a+b;

System.out.println(sum);}}

|||||||||||||||||||||||||

WHY DO WE NEED OJS? Test on multiple data Optimize code:

Time complexitySpace complexity

Large Input

TIME COMPLEXITY Time limit Input Constraints

INSTEAD OF THIS

public static void main(String args[])throws IOException{

BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

String str=new String();str=br.readLine();char c;for(int i=0; i<str.length(); i++){

c=str[i];System.out.println(c);

}

}

WE USE THISpublic static void main(String args[])throws IOException{

BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

String str=new String();str=br.readLine();char c;int len=str.length()for(int i=0; i<len; i++){

c=str[i];System.out.println(c);

}

}

SPACE COMPLEXITY

Example 1

vs

Example2

PRACTICES TO CONSIDER

Input Methods:Scanner << BufferedReader <<

BufferedInputStream Output Methods:

PrintWriter, PrintStream >> System.out.print

Input and Output Format

** ** * ** * * ** * * * *

** ** * ** * * ** * * * *

Expected Output

Ouput by Your Code

EXAMPLES SPOJ UVa TopCoder CodeForces CodeChef HackerRank HackerEarth

CODECHEF

Class name - Main DO NOT PRINT (“Enter a number”)

MOSS – THE BOSS

Plagiarism reporter Copy Case Different Variables

ANY QUESTION

S?

CONTACT US

MANSI JAIN (TE IT A):l mansi.j@somaiya.edu

KRUSHI GADA (TE IT A):l krushi.gada@somaiya.edu

VRISHABH LAKHANI (TE IT B):l vrishabh.l@somaiya.edu

THANK YOU