Longest palindrome

#include <iostream>
#include <string>
 
using namespace std;
 
int oddLength[1000005], evenLength[1000005];
 
string solve(string &s, int n)
{
 
    for (int i = 0, left = 0, right = -1; i < n; i++)
    {
 
        int length = (i > right)
                         ? 1
                         : min(oddLength[left + right - i],
                               right - i + 1);
 
        while (0 <= i - length && i + length < n && s[i - length] == s[i + length])
        {
            length++;
        }
 
        oddLength[i] = length--;
 
        if (i + length > right)
        {
            left = i - length;
            right = i + length;
        }
    }
 
    for (int i = 0, left = 0, right = -1; i < n; i++)
    {
 
        int length = (i > right)
                         ? 0
                         : min(evenLength[left + right - i + 1],
                               right - i + 1);
 
        while (0 <= i - length - 1 && i + length < n && s[i - length - 1] == s[i + length])
        {
            length++;
        }
 
        evenLength[i] = length--;
 
        if (i + length > right)
        {
            left = i - length - 1;
            right = i + length;
        }
    }
 
    int maxLength = 0, center = -1;
    for (int i = 0; i < n; i++)
    {
 
        if (oddLength[i] * 2 - 1 > maxLength)
        {
            maxLength = oddLength[i] * 2 - 1;
            center = i;
        }
        if (evenLength[i] * 2 > maxLength)
        {
            maxLength = evenLength[i] * 2;
            center = i;
        }
    }
 
    if (maxLength % 2 == 1)
        return s.substr(center - maxLength / 2, maxLength);
    return s.substr(center - maxLength / 2, maxLength);
}
 
int main()
{
 
    string s ;
    getline(cin, s);
    int n = s.size();
 
    cout << solve(s, n);
 
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED