Longest palindrome

#include <iostream>
#include <vector>
#include <algorithm>
#include <bitset>
#include <string>

using namespace std;

int min(int a, int b) 
{ 
    int res = a; 
    if(b < a) 
        res = b; 
    return res; 
} 

int main() {
    string s;
    cin >> s;
    int n = s.size(); 
    if(n == 0) {
        cout << "" << endl;
        return 0;
    }
    n = 2*n + 1;
    int L[n]; 
    L[0] = 0; 
    L[1] = 1; 
    int C = 1; 
    int R = 2; 
    int i = 0; 
    int iMirror; 
    int maxLen = 0; 
    int maxCenterPosition = 0; 
    int diff = -1; 
    
    for (i = 2; i < n; i++) 
    { 
        iMirror = 2*C-i; 
        L[i] = 0; 
        diff = R - i; 
        if(diff > 0) 
            L[i] = min(L[iMirror], diff); 

        while ( ((i + L[i]) < n && (i - L[i]) > 0) && ( ((i + L[i] + 1) % 2 == 0) || (s[(i + L[i] + 1)/2] == s[(i - L[i] - 1)/2] ))) { 
            L[i]++; 
        } 

        if(L[i] > maxLen) { 
            maxLen = L[i]; 
            maxCenterPosition = i; 
        } 

        if (i + L[i] > R) { 
            C = i; 
            R = i + L[i]; 
        } 

    } 
    int start = (maxCenterPosition - maxLen)/2; 
    
    cout << s.substr(start, maxLen) << endl; 
} 

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