About output format in SPOJ

[ruczhangxy]

I'm new to SPOJ and I have some questions concerning Java.
Days ago I ACed a problem but I decided to submit another code and in the new code I put all the output to a StringBuilder and print the StringBuilder in the end of the program, instead of using System.out.println for each test case. By doing this I thought I may save some time.

But the problem is that SPOJ kept giving me wrong answer. And the only change I made is replaced several System.out.println with one System.out.print(StringBuilder).
And I'm sure I added all the line separator the problem requires.
Any one know any possible solution?

Here is my code and the problem id is 5

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
public class Main {
    /**
 * 5. The Next Palindrome
 * 
 * @param args
 */
public static void main(String[] args) {
	// String str = "9899";
	// System.out.println(getNextPalin(str));
	doFunc();
}

private static void doFunc() {
	try {
		BufferedReader reader = new BufferedReader(new InputStreamReader(
				System.in));
		String str = reader.readLine();
		int count = Integer.valueOf(str);
		List<String> list = new ArrayList<String>();
		for (int i = 0; i < count; ++i) {
			str = reader.readLine();
			list.add(str);
		}
		reader.close();

		String ls = System.getProperty("line.separator");
		StringBuilder sb = new StringBuilder();
		for (String s : list) {
			sb.append(getNextPalin(s) + ls);
		}
		System.out.print(sb);
	} catch (NumberFormatException e) {
		e.printStackTrace();
	} catch (IOException e) {
		e.printStackTrace();
	}

}

private static String getNextPalin(String str) {
	char[] buffer = str.toCharArray();
	if (buffer.length == 1) {
		if (buffer[0] == '9') {
			return "11";
		} else {
			return String.valueOf(buffer[0] + 1);
		}
	}
	boolean allNine = true;
	for (char c : buffer) {
		if (c != '9') {
			allNine = false;
			break;
		}
	}
	if (allNine) {
		char[] r = new char[buffer.length + 1];
		r[0] = '1';
		r[r.length - 1] = '1';
		for (int i = 1; i < r.length - 1; ++i) {
			r[i] = '0';
		}
		return String.valueOf(r);
	}

	int rightPointer = str.length() - 1;
	int leftPointer = 0;
	boolean needsUp = false;
	boolean equalOK = false;
	while (rightPointer > leftPointer) {
		char rightChar = buffer[rightPointer];
		char leftChar = buffer[leftPointer];
		buffer[rightPointer--] = buffer[leftPointer++];

		if (rightChar == leftChar) {
			if (!equalOK) {
				needsUp = true;
			}
		} else if (rightChar < leftChar) {
			// This means direct change.
			// buffer[rightPointer] = buffer[leftPointer];
			needsUp = false;
			equalOK = true;
		} else {
			needsUp = true;
		}
	}

	if (needsUp) {

		if (rightPointer < leftPointer) {
			++rightPointer;
			--leftPointer;
		}
		while (buffer[leftPointer] == '9') {
			buffer[leftPointer] = '0';
			buffer[rightPointer] = '0';
			if (leftPointer > 0) {
				--leftPointer;
				++rightPointer;
			}
		}

		// Just raise.
		buffer[leftPointer] += 1;
		if (leftPointer != rightPointer) {
			buffer[rightPointer] += 1;
		}
	}

	return String.valueOf(buffer);
}
}

[TripleM_sof]

You should be able to test your code by yourself quite easily First thing I did was test your code on some small numbers between 1 and 9 and immediately got the wrong answer for all of them. You have a casting problem - when concenating a String with a char it treats it as a char, but adding 1 to a char treats it as an integer - try those test cases and you'll see why.

[ruczhangxy]

You should be able to test your code by yourself quite easily First thing I did was test your code on some small numbers between 1 and 9 and immediately got the wrong answer for all of them. You have a casting problem - when concenating a String with a char it treats it as a char, but adding 1 to a char treats it as an integer - try those test cases and you'll see why.

Thanks for the tip