Working on my own machine but SIGABRT on SPOJ - c++

Question

I'm working on the Next Palindrome problem on SPOJ http://www.spoj.com/problems/PALIN/. My code works fine on my own machine, but SPOJ gives me SIGABRT. I'm using C++ 4.9.2
"A positive integer is called a palindrome if its representation in the decimal system is the same when read from left to right and from right to left. For a given positive integer K of not more than 1000000 digits, write the value of the smallest palindrome larger than K to output. Numbers are always displayed without leading zeros.
Input
The first line contains integer t, the number of test cases. Integers K are given in the next t lines.
Output
For each K, output the smallest palindrome larger than K."
#include<iostream>
#include<vector>
using namespace std;
// turn 9 to 10
void round(vector<int> &input,int index) {
int len = input.size();
input[index] = 0;
input[len-index-1] = 0;
// if it is the first digit, add 1 in the front
if (index == 0) {
input.insert(input.begin(),1);
}
else {
input[index-1] ++;
input[len-index] ++;
}
}
// find the next palindrome
int palin(vector<int> &input) {
int len = input.size();
bool large = true;
bool small = true;
bool eqal = true;
// if it is a single digit
if (len == 1) {
if (input[0] == 9) {
input[0] = 11;
}
else {
input[0] ++;
}
return 1;
}
// start from the one before the middle
int index = len / 2 - 1;
while (index >= 0) {
len = input.size();
// the number supposed to be the same as input[index]
int rfl = len-index-1;
// keep record for if the updated number is smaller/equal to the original
if (input[index] > input[rfl]) {small = false; eqal = false;}
else if (input[index] < input[rfl]) {large = false; small = true; eqal = false;}
else {small = false;}
if (input[index] == 10) {round(input,index);}
else {
input[rfl] = input[index];
}
index --;
};
// restart from the one before the middle
index = (int)input.size() / 2 - 1;
// unless all digits on the left are larger than right/the more left digits are larger but some closer to the middle are smaller or equal, increase the number
if (!large || small || eqal) {
len = input.size();
if (len % 2 == 1) { // odd
if (input[index+1] == 9) {
round(input,index+1);
}
else {input[index+1] ++;}
}
else { // even
if (input[index] == 9) {
round(input,index);
}
else {
input[index-1] ++; input[index + 1] ++;
}
}
// go over the digits again to make sure it is a palindrome
while (index >= 0) {
if (input[index] == 10) {
round(input,index);
}
input[input.size()-index-1] = input[index];
index --;
}
}
return 0;
}
int main() {
int count; // how many numbers are there
cin >> count;
string buffer; // temporary to store each line of input
for (int j=0;j<count;++j) {
vector<int> number;
cin >> buffer;
if (cin.fail() || buffer.size() == 0) { // not a number or length==0
return 1;
}
for (int k=0;k<(int)buffer.size();k++) {
int temp = buffer[k] - '0'; // convert ASCII to int
number.push_back(temp); // construct vector
}
palin(number);
for (int i=0;i<(int)number.size();i++) {
cout << number[i];
}
cout << endl;
}
return 0;
}

Answer 1

Honestly, a brute force method would be inefficient, but would be pretty clear to code. Here, I just keep iterating through numbers until I find a palindrome, for each of the numbers:
http://coliru.stacked-crooked.com/a/2c7ac595d7c2cfa7
#include <iostream>
#include <stack>
#include <string>
#include <vector>
int main() {
int count; // how many numbers are there
std::cin >> count;
std::string buffer;
//two vectors to store output
std::vector<long int> input;
std::vector<long int> output;
//take the inputs
for(int i = 0; i < count; ++i) {
std::cin >> buffer;
input.push_back(std::stoi(buffer));
buffer.clear();
}
//check that we have the inputs
for(auto it : input) {
std::cout << it << std::endl;
}
//lambda to test for palindromes
auto is_palindrome = [](long int n) {
auto str = std::to_string(n);
std::stack<char> stack;
//Load each character into the stack
for(auto it : str) {
stack.push(it);
}
//Use the property of a stack to take out in a reverse order
for(size_t i = 0; !stack.empty(); stack.pop()) {
if (stack.top() != str[i])
return false;
else
++i;
}
return true;
};
//test for the palindromes; iterate
for(auto it : input) {
int n;
for (n = it+1; ; ++n) {
if(is_palindrome(n))
break;
else
continue;
}
output.push_back(n);
}
//output the outputs
for(auto it : output) {
std::cout << "next palindrome: " << it << '\n';
}
return 0;
}