首先是问题所在：
如果一个正整数在十进制系统中的表示在从左到右和从右到左读取时相同，则称为回文。对于给定的不超过 1000000 位的正整数 K，将大于 K 的最小回文的值写入输出。数字始终显示不带前导零。
输入：第一行包含整数 t，即测试用例的数量。整数 K 在接下来的 t 行中给出。
输出：对于每个 K，输出大于 K 的最小回文数。示例
输入：
2
808
2133
输出：
818
2222
其次，这是我的代码：
// I know it is bad practice to not cater for erroneous input,
// however for the purpose of the execise it is omitted
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.lang.Exception;
import java.math.BigInteger;
public class Main
{
public static void main(String [] args){
try{
Main instance = new Main(); // create an instance to access non-static
// variables
// Use java.util.Scanner to scan the get the input and initialise the
// variable
Scanner sc=null;
BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
String input = "";
int numberOfTests = 0;
String k; // declare any other variables here
if((input = r.readLine()) != null){
sc = new Scanner(input);
numberOfTests = sc.nextInt();
}
for (int i = 0; i < numberOfTests; i++){
if((input = r.readLine()) != null){
sc = new Scanner(input);
k=sc.next(); // initialise the remainder of the variables sc.next()
instance.palindrome(k);
} //if
}// for
}// try
catch (Exception e)
{
e.printStackTrace();
}
}// main
public void palindrome(String number){
StringBuffer theNumber = new StringBuffer(number);
int length = theNumber.length();
int left, right, leftPos, rightPos;
// if incresing a value to more than 9 the value to left (offset) need incrementing
int offset, offsetPos;
boolean offsetUpdated;
// To update the string with new values
String insert;
boolean hasAltered = false;
for(int i = 0; i < length/2; i++){
leftPos = i;
rightPos = (length-1) - i;
offsetPos = rightPos -1; offsetUpdated = false;
// set values at opposite indices and offset
left = Integer.parseInt(String.valueOf(theNumber.charAt(leftPos)));
right = Integer.parseInt(String.valueOf(theNumber.charAt(rightPos)));
offset = Integer.parseInt(String.valueOf(theNumber.charAt(offsetPos)));
if(left != right){
// if r > l then offest needs updating
if(right > left){
// update and replace
right = left;
insert = Integer.toString(right);
theNumber.replace(rightPos, rightPos + 1, insert);
offset++; if (offset == 10) offset = 0;
insert = Integer.toString(offset);
theNumber.replace(offsetPos, offsetPos + 1, insert);
offsetUpdated = true;
// then we need to update the value to left again
while (offset == 0 && offsetUpdated){
offsetPos--;
offset =
Integer.parseInt(String.valueOf(theNumber.charAt(offsetPos)));
offset++; if (offset == 10) offset = 0;
// replace
insert = Integer.toString(offset);
theNumber.replace(offsetPos, offsetPos + 1, insert);
}
// finally incase right and offset are the two middle values
left = Integer.parseInt(String.valueOf(theNumber.charAt(leftPos)));
if (right != left){
right = left;
insert = Integer.toString(right);
theNumber.replace(rightPos, rightPos + 1, insert);
}
}// if r > l
else
// update and replace
right = left;
insert = Integer.toString(right);
theNumber.replace(rightPos, rightPos + 1, insert);
}// if l != r
}// for i
System.out.println(theNumber.toString());
}// palindrome
}
最后我的解释和问题。
My code compares either end and then moves in
if left and right are not equal
if right is greater than left
(increasing right past 9 should increase the digit
to its left i.e 09 ---- > 10) and continue to do
so if require as for 89999, increasing the right
most 9 makes the value 90000
before updating my string we check that the right
and left are equal, because in the middle e.g 78849887
we set the 9 --> 4 and increase 4 --> 5, so we must cater for this.
问题出在在线裁判系统 spoj.pl 上。我的代码适用于所有可以提供的测试，但是当我提交它时，我得到一个超出时间限制的错误并且我的答案不被接受。
有没有人对我如何改进我的算法有任何建议。在写这个问题时，我认为代替我的 while (offset == 0 && offsetUpdated) 循环，我可以使用布尔值来确保我在下一次 [i] 迭代中增加偏移量。确认我的 chang 或任何建议将不胜感激，如果我需要让我的问题更清楚，也请告诉我。