Submission #887949

#	Time	Username	Problem	Language	Result	Execution time	Memory
887949		phong	Palindromes (APIO14_palindrome)	C++17	Compilation error	0 ms	0 KiB

palindrome

#include<bits/stdc++.h>

#define ll long long
const int nmax = 3e5 + 5;
const ll oo = 1e18;
const int lg = 18;
const int tx = 2;
const ll base = 31;
#define pii pair<int, int>
#define fi first
#define se second
#define debug(a, n) for(int i = 1; i <= n; ++i) cout << a[i] << ' ';
using namespace std;

int mod[] = {(int)1e9 + 7, (int)1e9 + 9};
int n, cur = 0;
string s;
int pw[2][nmax], h[2][nmax];
int D_odd[nmax];
int D_even[nmax];

void Calc_D_odd() {
    int L = 1;
    int R = 0;
    for(int i = 1 ; i <= n; i++) {
        if(i > R) D_odd[i] = 0;
        else D_odd[i] = min(R - i, D_odd[L + (R - i)]);
        while(i - D_odd[i] - 1 > 0 && i + D_odd[i] + 1 <= n && s[i - D_odd[i] - 1] == s[i + D_odd[i] + 1]) {
            D_odd[i]++;
        }

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

void Calc_D_even() {
    int L = 1;
    int R = 0;
    for(int i = 1 ; i < n; i++) {
        int j = i + 1;
        if(j > R) D_even[i] = 0;
        else D_even[i] = min(R - j + 1, D_even[L + (R - j)]);
        while(i - D_even[i] > 0 && j + D_even[i] <= n && s[i - D_even[i]] == s[j + D_even[i]]) {
            D_even[i]++;
        }
        if(i + D_even[i] > R) {
            R = i + D_even[i];
            L = j - D_even[i];
        }
    }
}


void Init(){
    for(int j = 0; j < tx; ++j) pw[j][0] = 1;
    for(int i = 1, j; i <= n; ++i){
        for(int j = 0; j < tx; ++j){
            pw[j][i] = 1ll * pw[j][i - 1] * base % mod[j];
            h[j][i] = (1ll * h[j][i - 1] * base + s[i] - 'a' + 1) % mod[j];
        }
    }
}
int get(int l, int r, int ix){
    return (h[ix][r] - 1ll * h[ix][l - 1] * pw[ix][r - l + 1] + 1ll * mod[ix] * mod[ix]) % mod[ix];
}

unordered_map<pii, bool> mp;
unordered_map<pii, int>  ind;
int cnt[nmax], f[nmax];
int b[nmax];
vector<int> adj[nmax];

void update(int l, int r){
    bool ok = 1;
    pii x;int sz = 0;
    while(l <= r){
        x = {get(l, r, 0), get(l, r, 1)};
        if(!mp[x]){
            ind[x] = ++cur;
            b[++sz] = cur;
            if(ok){
                f[cur]++;
                ok = 0;
            }
            cnt[cur] = r - l + 1;
            mp[x] = 1;
        }
        else{
            int id = ind[x];
            b[++sz] = id;
            if(ok) f[id]++;
            break;
        }
        ++l, --r;
    }
    if(l > r) b[++sz] = 0;
    for(int i = 1, x, y; i < sz; ++i){
        x = b[i], y = b[i + 1];
        adj[y].push_back(x);
    }
}
void dfs(int u){
    for(auto v : adj[u]){
        dfs(v);
        f[u] += f[v];
    }
}
main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
//    freopen("code.inp", "r", stdin);
//    freopen("code.out", "w", stdout);
    cin >> s;
    n = s.size(); s = ' ' + s + ' ';
    Init();
    Calc_D_odd();
    Calc_D_even();
    for(int i = 1; i <= n; ++i){
        update(i - D_odd[i], i + D_odd[i]);
        if(i < n) update(i - D_even[i] + 1, i + D_even[i]);
    }
    dfs(0);

    ll ans = 0;
    for(int i = 1; i <= cur; ++i){
        ans = max(ans, 1ll * f[i] * cnt[i]);
    }
    cout << ans;
}
/*

*/

Compilation message (stderr)

palindrome.cpp: In function 'void Init()':
palindrome.cpp:59:20: warning: unused variable 'j' [-Wunused-variable]
   59 |     for(int i = 1, j; i <= n; ++i){
      |                    ^
palindrome.cpp: At global scope:
palindrome.cpp:70:26: error: use of deleted function 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map() [with _Key = std::pair<int, int>; _Tp = bool; _Hash = std::hash<std::pair<int, int> >; _Pred = std::equal_to<std::pair<int, int> >; _Alloc = std::allocator<std::pair<const std::pair<int, int>, bool> >]'
   70 | unordered_map<pii, bool> mp;
      |                          ^~
In file included from /usr/include/c++/10/unordered_map:47,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/unordered_map.h:141:7: note: 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map() [with _Key = std::pair<int, int>; _Tp = bool; _Hash = std::hash<std::pair<int, int> >; _Pred = std::equal_to<std::pair<int, int> >; _Alloc = std::allocator<std::pair<const std::pair<int, int>, bool> >]' is implicitly deleted because the default definition would be ill-formed:
  141 |       unordered_map() = default;
      |       ^~~~~~~~~~~~~
/usr/include/c++/10/bits/unordered_map.h:141:7: error: use of deleted function 'std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::_Hashtable() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, bool>; _Alloc = std::allocator<std::pair<const std::pair<int, int>, bool> >; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, false, true>]'
In file included from /usr/include/c++/10/unordered_map:46,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/hashtable.h:451:7: note: 'std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::_Hashtable() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, bool>; _Alloc = std::allocator<std::pair<const std::pair<int, int>, bool> >; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, false, true>]' is implicitly deleted because the default definition would be ill-formed:
  451 |       _Hashtable() = default;
      |       ^~~~~~~~~~
/usr/include/c++/10/bits/hashtable.h:451:7: error: use of deleted function 'std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, _Hash, _Traits>::_Hashtable_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, bool>; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, false, true>]'
In file included from /usr/include/c++/10/bits/hashtable.h:35,
                 from /usr/include/c++/10/unordered_map:46,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/hashtable_policy.h:1791:5: note: 'std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, _Hash, _Traits>::_Hashtable_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, bool>; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, false, true>]' is implicitly deleted because the default definition would be ill-formed:
 1791 |     _Hashtable_base() = default;
      |     ^~~~~~~~~~~~~~~
/usr/include/c++/10/bits/hashtable_policy.h:1791:5: error: use of deleted function 'std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, std::__detail::_Default_ranged_hash, true>::_Hash_code_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, bool>; _ExtractKey = std::__detail::_Select1st; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing]'
/usr/include/c++/10/bits/hashtable_policy.h:1368:7: note: 'std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, std::__detail::_Default_ranged_hash, true>::_Hash_code_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, bool>; _ExtractKey = std::__detail::_Select1st; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing]' is implicitly deleted because the default definition would be ill-formed:
 1368 |       _Hash_code_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/10/bits/hashtable_policy.h:1368:7: error: use of deleted function 'std::__detail::_Hashtable_ebo_helper<_Nm, _Tp, true>::_Hashtable_ebo_helper() [with int _Nm = 1; _Tp = std::hash<std::pair<int, int> >]'
/usr/include/c++/10/bits/hashtable_policy.h:1112:7: note: 'std::__detail::_Hashtable_ebo_helper<_Nm, _Tp, true>::_Hashtable_ebo_helper() [with int _Nm = 1; _Tp = std::hash<std::pair<int, int> >]' is implicitly deleted because the default definition would be ill-formed:
 1112 |       _Hashtable_ebo_helper() = default;
      |       ^~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/10/bits/hashtable_policy.h:1112:7: error: use of deleted function 'std::hash<std::pair<int, int> >::hash()'
In file included from /usr/include/c++/10/string_view:42,
                 from /usr/include/c++/10/bits/basic_string.h:48,
                 from /usr/include/c++/10/string:55,
                 from /usr/include/c++/10/bits/locale_classes.h:40,
                 from /usr/include/c++/10/bits/ios_base.h:41,
                 from /usr/include/c++/10/ios:42,
                 from /usr/include/c++/10/istream:38,
                 from /usr/include/c++/10/sstream:38,
                 from /usr/include/c++/10/complex:45,
                 from /usr/include/c++/10/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:54,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/functional_hash.h:101:12: note: 'std::hash<std::pair<int, int> >::hash()' is implicitly deleted because the default definition would be ill-formed:
  101 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/10/bits/functional_hash.h:101:12: error: no matching function for call to 'std::__hash_enum<std::pair<int, int>, false>::__hash_enum()'
/usr/include/c++/10/bits/functional_hash.h:82:7: note: candidate: 'std::__hash_enum<_Tp, <anonymous> >::__hash_enum(std::__hash_enum<_Tp, <anonymous> >&&) [with _Tp = std::pair<int, int>; bool <anonymous> = false]'
   82 |       __hash_enum(__hash_enum&&);
      |       ^~~~~~~~~~~
/usr/include/c++/10/bits/functional_hash.h:82:7: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/10/bits/functional_hash.h:101:12: error: 'std::__hash_enum<_Tp, <anonymous> >::~__hash_enum() [with _Tp = std::pair<int, int>; bool <anonymous> = false]' is private within this context
  101 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/10/bits/functional_hash.h:83:7: note: declared private here
   83 |       ~__hash_enum();
      |       ^
In file included from /usr/include/c++/10/bits/hashtable.h:35,
                 from /usr/include/c++/10/unordered_map:46,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/hashtable_policy.h:1112:7: error: use of deleted function 'std::hash<std::pair<int, int> >::~hash()'
 1112 |       _Hashtable_ebo_helper() = default;
      |       ^~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/10/string_view:42,
                 from /usr/include/c++/10/bits/basic_string.h:48,
                 from /usr/include/c++/10/string:55,
                 from /usr/include/c++/10/bits/locale_classes.h:40,
                 from /usr/include/c++/10/bits/ios_base.h:41,
                 from /usr/include/c++/10/ios:42,
                 from /usr/include/c++/10/istream:38,
                 from /usr/include/c++/10/sstream:38,
                 from /usr/include/c++/10/complex:45,
                 from /usr/include/c++/10/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:54,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/functional_hash.h:101:12: note: 'std::hash<std::pair<int, int> >::~hash()' is implicitly deleted because the default definition would be ill-formed:
  101 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/10/bits/functional_hash.h:101:12: error: 'std::__hash_enum<_Tp, <anonymous> >::~__hash_enum() [with _Tp = std::pair<int, int>; bool <anonymous> = false]' is private within this context
/usr/include/c++/10/bits/functional_hash.h:83:7: note: declared private here
   83 |       ~__hash_enum();
      |       ^
In file included from /usr/include/c++/10/bits/hashtable.h:35,
                 from /usr/include/c++/10/unordered_map:46,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/hashtable_policy.h:1368:7: error: use of deleted function 'std::__detail::_Hashtable_ebo_helper<1, std::hash<std::pair<int, int> >, true>::~_Hashtable_ebo_helper()'
 1368 |       _Hash_code_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/10/bits/hashtable_policy.h:1109:12: note: 'std::__detail::_Hashtable_ebo_helper<1, std::hash<std::pair<int, int> >, true>::~_Hashtable_ebo_helper()' is implicitly deleted because the default definition would be ill-formed:
 1109 |     struct _Hashtable_ebo_helper<_Nm, _Tp, true>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/10/bits/hashtable_policy.h:1109:12: error: use of deleted function 'std::hash<std::pair<int, int> >::~hash()'
/usr/include/c++/10/bits/hashtable_policy.h:1791:5: error: use of deleted function 'std::__detail::_Hash_code_base<std::pair<int, int>, std::pair<const std::pair<int, int>, bool>, std::__detail::_Select1st, std::hash<std::pair<int, int> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, true>::~_Hash_code_base()'
 1791 |     _Hashtable_base() = default;
      |     ^~~~~~~~~~~~~~~
/usr/include/c++/10/bits/hashtable_policy.h:1341:12: note: 'std::__detail::_Hash_code_base<std::pair<int, int>, std::pair<const std::pair<int, int>, bool>, std::__detail::_Select1st, std::hash<std::pair<int, int> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, true>::~_Hash_code_base()' is implicitly deleted because the default definition would be ill-formed:
 1341 |     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1342 |       _Default_ranged_hash, true>
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/10/bits/hashtable_policy.h:1341:12: error: use of deleted function 'std::__detail::_Hashtable_ebo_helper<1, std::hash<std::pair<int, int> >, true>::~_Hashtable_ebo_helper()'
In file included from /usr/include/c++/10/unordered_map:46,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/hashtable.h:451:7: error: use of deleted function 'std::__detail::_Hashtable_base<std::pair<int, int>, std::pair<const std::pair<int, int>, bool>, std::__detail::_Select1st, std::equal_to<std::pair<int, int> >, std::hash<std::pair<int, int> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<true, false, true> >::~_Hashtable_base()'
  451 |       _Hashtable() = default;
      |       ^~~~~~~~~~
In file included from /usr/include/c++/10/bits/hashtable.h:35,
                 from /usr/include/c++/10/unordered_map:46,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/hashtable_policy.h:1725:10: note: 'std::__detail::_Hashtable_base<std::pair<int, int>, std::pair<const std::pair<int, int>, bool>, std::__detail::_Select1st, std::equal_to<std::pair<int, int> >, std::hash<std::pair<int, int> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<true, false, true> >::~_Hashtable_base()' is implicitly deleted because the default definition would be ill-formed:
 1725 |   struct _Hashtable_base
      |          ^~~~~~~~~~~~~~~
/usr/include/c++/10/bits/hashtable_policy.h:1725:10: error: use of deleted function 'std::__detail::_Hash_code_base<std::pair<int, int>, std::pair<const std::pair<int, int>, bool>, std::__detail::_Select1st, std::hash<std::pair<int, int> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, true>::~_Hash_code_base()'
palindrome.cpp:71:26: error: use of deleted function 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map() [with _Key = std::pair<int, int>; _Tp = int; _Hash = std::hash<std::pair<int, int> >; _Pred = std::equal_to<std::pair<int, int> >; _Alloc = std::allocator<std::pair<const std::pair<int, int>, int> >]'
   71 | unordered_map<pii, int>  ind;
      |                          ^~~
In file included from /usr/include/c++/10/unordered_map:47,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/unordered_map.h:141:7: note: 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map() [with _Key = std::pair<int, int>; _Tp = int; _Hash = std::hash<std::pair<int, int> >; _Pred = std::equal_to<std::pair<int, int> >; _Alloc = std::allocator<std::pair<const std::pair<int, int>, int> >]' is implicitly deleted because the default definition would be ill-formed:
  141 |       unordered_map() = default;
      |       ^~~~~~~~~~~~~
/usr/include/c++/10/bits/unordered_map.h:141:7: error: use of deleted function 'std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::_Hashtable() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, int>; _Alloc = std::allocator<std::pair<const std::pair<int, int>, int> >; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, false, true>]'
In file included from /usr/include/c++/10/unordered_map:46,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/hashtable.h:451:7: note: 'std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::_Hashtable() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, int>; _Alloc = std::allocator<std::pair<const std::pair<int, int>, int> >; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, false, true>]' is implicitly deleted because the default definition would be ill-formed:
  451 |       _Hashtable() = default;
      |       ^~~~~~~~~~
/usr/include/c++/10/bits/hashtable.h:451:7: error: use of deleted function 'std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, _Hash, _Traits>::_Hashtable_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, int>; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, false, true>]'
In file included from /usr/include/c++/10/bits/hashtable.h:35,
                 from /usr/include/c++/10/unordered_map:46,
                 from /usr/include/c++/10/functional:61,
                 from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/10/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
                 from palindrome.cpp:1:
/usr/include/c++/10/bits/hashtable_policy.h:1791:5: note: 'std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, _Hash, _Traits>::_Hashtable_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, int>; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _H1 = std::hash<std::pair<int, int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, false, true>]' is implicitly deleted because the default definition would be ill-formed:
 1791 |     _Hashtable_base() = default;
      |     ^~~~~~~~~~~~