F.A.Q

F.A.Q / 常见问题解答

Q Which programming languages can I use and what are the compiler options?

A Online Judge supports C, C++ and Java, and uses GCC, G++ and JDK6 compiler. The version and compile options are:

GCC (v4.7.2): gcc.exe src.c -o test.exe
G++ (v4.7.2): g++.exe src.c -o test.exe
JDK6 (Update 45): javac.exe -encoding utf-8 Main.java

Q How can I write program at Online Judge?

A Your program should read input from stdin("Standard Input") and write output to stdout("Standard Output").

This is a sample solution for the A + B problem (Problem 1000) in the C language:

#include <stdio.h>
int main()
{
    int a, b;
    scanf("%d%d", &a, &b);
    printf("%d\n", a + b);
    return 0;
}

And the same problem in C++:

#include <iostream>
using namespace std;
int main()
{
    int a, b;
    cin >> a >> b;
    cout << a + b << endl;
    return 0;
}

And the same problem in Java:

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();
        System.out.println(a + b);
    }
}

Q What are the meanings of the judge's replies?

A Here is a list of the Judge's replies and their meaning:

Pending / Rejudge Pending: Your program is in the waiting queue, please wait a moment.
Judging: Your program is judging on the server.
Compile Error: The compiler fails to compile your program, you can view more information in "Online Status".
Runtime Error: Your program failed during the execution, you can view more information in "Online Status".
Time Limit Exceeded: Your program tried to run during too much time.
Memory Limit Exceeded: Your program tried to use more memory than the judge default settings.
Output Limit Exceeded: Your program tried to write too much information. Be sure that your program has no infinite loop.
Wrong Answer: Your output is incorrect. Note that, the judging data is far difficult than the sample.
Presentation Error: Your output format is not exactly the same as the sample output. Check your output for spaces and blank lines.
Accepted: Your program is correct and has passed the test.

Q Why did my C / C++ problem get a Compile Error?

A The judger use GCC / G++ complier, that may be different from VC++, for example:

The main function must be declared as int, and you must return 0 at the end of main function, and void main will end up with a Compile Error.
The function itoa is not in ANSI Standard, so you need to use other solution.
The 64-bit integer __int64 is not in ANSI Standard, you can use long long instead. Because we use Windows operation system, you should use "%I64d" instead of "%lld", if you use scanf and printf.

Q How can I read input data until the end?

A If you meet a problem doesn't give the number of case, You can do it like this:

Operation

C++

Java

To read numbers

int n;
while(scanf("%d", &n) != EOF)
{
　　//Do Something
}

C++

int n;
while (cin >> n)
{
　　//Do Something
}

Java

Scanner in = new Scanner(System.in);
while (in.hasNextInt()){
    int n = in.nextInt();
    //Do Something
}

To read characters

char w;
while ((w = getchar()) != EOF)
{
　　//Do Something
}

C++

char w;
while (cin.get(w))
{
　　//Do Something
}

Java

Scanner in = new Scanner(System.in);
while (in.hasNext()){
    string w = in.next();
    //Do Something
}

To read lines

char l[1024];
while(gets(l))
{
　　//Do Something
}

C++

string l;
while (getline(cin, l))
{
　　//Do Something
}

Java

Scanner in = new Scanner(System.in);
while (in.hasNextLine()){
    string l = in.nextLine();
    //Do Something
}

Q What is the maximum size of program that can be submitted?

A The maximal size of program is 32767 bytes (32KB).