Submission #955797

#	Time	Username	Problem	Language	Result	Execution time	Memory
955797		Neco_arc	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	107 ms	28756 KiB

palindromic

#include <bits/stdc++.h>

#define ll long long
#define ull unsigned long long
#define all(x) x.begin(), x.end()
#define Neco "Palindromic Partitions"
#define resp(x) sort(all(x)), x.resize(unique(all(x)) - x.begin())
#define getbit(x,i) ((x >> i)&1)
#define _left id * 2, l, mid
#define _right id * 2 + 1, mid + 1, r
#define cntbit(x) __builtin_popcountll(x)
#define fi(i, a, b) for(int i = a; i <= b; i++)
#define fid(i, a, b) for(int i = a; i >= b; i--)
#define maxn (int) 1e6 + 7

using namespace std;

const ll mod = 972663749;
const ll base = 911382323;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

ll GetRandom(ll l, ll r)
{
    return uniform_int_distribution<ll> (l, r)(rng);
}

int n;
ll H[maxn], pw[maxn];
string a;

ll get(int l, int r) {
    return (H[r] - H[l - 1] * pw[r - l + 1] + mod * mod) % mod;
}

void solve()
{

    cin >> a;
    n = a.size(), a = ' ' + a;

    fi(i, 1, n) H[i] = (H[i - 1] * base + a[i] - 'a') % mod;

    int l = 1, r = n;

//    cout << get(3, 3) << " " << get(5, 5);

//
    int ans = 0;
    while(l <= r)
    {
        int R = l, L = r;
        while(R < L) {
            if(get(l, R) != get(L, r)) ++R, --L;
            else
            {
                l = R + 1, r = L - 1;
                ans += 2;
                break;
            }
        }

        if(R >= L) {
            ans ++;
            break;
        }
    }

    cout << ans << '\n';

}


int main()
{

    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    if(fopen(Neco".inp", "r")) {
        freopen(Neco".inp", "r", stdin);
        freopen(Neco".out", "w", stdout);
    }


    int nTest = 1;
    cin >> nTest;

    pw[0] = 1;
    fi(i, 1, maxn - 2) pw[i] = (pw[i - 1] * base) % mod;

    while(nTest--)
    {
        solve();
    }


    return 0;
}

Compilation message (stderr)

palindromic.cpp: In function 'int main()':
palindromic.cpp:82:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |         freopen(Neco".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
palindromic.cpp:83:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |         freopen(Neco".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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