Submission #1312879

#	Time	Username	Problem	Language	Result	Execution time	Memory
1312879		the_commando_x	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	192 ms	18928 KiB

palindromic

// #pragma GCC optimize("O3")
#include <bits/stdc++.h>

using namespace std;

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;

using pii = pair<int, int>;
using vii = vector<pii>;
using vvii = vector<vii>;

using l = long long;
using vl = vector<l>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;

using pll = pair<l, l>;
using vll = vector<pll>;
using vvll = vector<vll>;

using d = double;
using vd = vector<d>;
using vvd = vector<vd>;
using vvvd = vector<vvd>;

using ld = long double;
using vld = vector<ld>;
using vvld = vector<vld>;
using vvvld = vector<vvld>;

using vb = vector<bool>;
using vvb = vector<vb>;
using pbb = pair<bool, bool>;
using vbb = vector<pbb>;

#define ff first
#define ss second

#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()

void setIO(string name = "")
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if (!name.empty())
    {
        (void)freopen((name + ".in").c_str(), "r", stdin);
        (void)freopen((name + ".out").c_str(), "w", stdout);
    }
}

const ld pi = 3.14159265358979323846;

const l LINF = 1e18;
const l INF = 1e9;

// const l MOD = 1e9 + 7;
// const l MOD = 998244353;

const l MAXN = 2e5 + 5;

const l MOD = (1 << 31) - 1;
const l BASE = 998244353;

void solve()
{
    string s;
    cin >> s;

    int n = s.length();

    vl pw(n + 1, 1);
    for (int i = 0; i < n; ++i)
        pw[i + 1] = (pw[i] * BASE) % MOD;

    vl pref(n + 1, 0);
    for (int i = 0; i < n; ++i)
        pref[i + 1] = (pref[i] * BASE + s[i]) % MOD;

    auto getHash = [&](int l, int r)
    {
        long long h = (pref[r + 1] - pw[r - l + 1] * pref[l] % MOD) % MOD;
        return (h + MOD) % MOD;
    };

    int cnt = 0;

    int l = 0, r = n - 1;
    for (int i = 0; l <= r; ++i)
        if (i == r)
        {
            ++cnt;
            break;
        }
        else if (getHash(l, i) == getHash(n - i - 1, r))
            cnt += 2, l = i + 1, r = (n - i - 1) - 1;

    cout << cnt << "\n";
}

int main()
{
    setIO("");

#ifndef ONLINE_JUDGE
    // setIO("filename");
#endif

    int t = 1;
    cin >> t;
    while (t--)
        solve();

    return 0;
}

Compilation message (stderr)

palindromic.cpp:68:25: warning: integer overflow in expression of type 'int' results in '2147483647' [-Woverflow]
   68 | const l MOD = (1 << 31) - 1;
      |               ~~~~~~~~~~^~~
palindromic.cpp: In function 'void setIO(std::string)':
palindromic.cpp:53:22: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   53 |         (void)freopen((name + ".in").c_str(), "r", stdin);
      |               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
palindromic.cpp:54:22: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |         (void)freopen((name + ".out").c_str(), "w", stdout);
      |               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 40 / 40