Longest palindrome

input/code.cpp: In function 'void Test()':
input/code.cpp:57:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   57 |     freopen("temp\\in.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
input/code.cpp: In function 'int main()':
input/code.cpp:63:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |     scanf("%s", s);
      |     ~~~~~^~~~~~~~~

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N=1000005;
 
char Ma[2*N];
int Mp[2*N];
void Manacher(char s[], int len)
{
    int l = 0;
    Ma[l++] = '$';
    Ma[l++] = '#';
    for(int i=0; i<len; i++)
    {
        Ma[l++] = s[i];
        Ma[l++] = '#';
    }
    Ma[l] = 0;
    int mx = 0, id = 0;
    for(int i=0; i<l; i++)
    {
        if(mx > i)
            Mp[i] = min(Mp[2*id - i], mx-i);
        else
            Mp[i] = 1;
 
        while(Ma[i + Mp[i]] == Ma[i - Mp[i]])
            Mp[i]++;
 
        if(Mp[i]+i > mx)
        {
            mx = i+Mp[i];
            id = i;
        }
    }
    mx = 0, id = 0;
    for(int i=0; i<l; i++)
        if(Mp[i] > mx)
        {
            mx = Mp[i];
            id = i;
        }
    string ans = "";
    if(Ma[id] != '#')
        ans = Ma[id];
    for(int i = 1; i<mx; i++)
    {
        char c = Ma[id - i];
        if(c != '#' && c != '$')
            ans = c + ans + c;
    }
    cout << ans;
}
 
void Test()
{
    freopen("temp\\in.txt", "r", stdin);
}
char s[N];
int main()
{
    // Test();
    scanf("%s", s);
    int len = strlen(s);
    Manacher(s, len);
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: TIME LIMIT EXCEEDED

Test 4

Verdict: TIME LIMIT EXCEEDED

Test 5

Verdict: TIME LIMIT EXCEEDED

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: TIME LIMIT EXCEEDED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: TIME LIMIT EXCEEDED