Submission #1313529

#	Time	Username	Problem	Language	Result	Execution time	Memory
1313529		Zbyszek99	Palindromic Partitions (CEOI17_palindromic)	C++20	100 / 100	82 ms	26668 KiB

palindromic

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

ll p = 2137;
ll P[2000001];
ll pref[1000001];

void solve()
{
    string s;
    cin >> s;
    s = "#"+s;
    int n = siz(s)-1;
    rep2(i,1,n) pref[i] = (pref[i-1]+P[i]*s[i])%MOD;
    int l = 1;
    int l2 = 1;
    int r = n;
    int r2 = n;
    int ans = 0;
    while(l2 < r2)
    {
        if(((pref[l2]-pref[l-1]+MOD)*P[n-l])%MOD == ((pref[r]-pref[r2-1]+MOD)*P[n-r2])%MOD)
        {
            ans += 2;
            l = l2+1;
            l2++;
            r = r2-1;
            r2--;
            continue;
        }
        l2++;
        r2--;
    }
    if(l <= r) ans++;
    cout << ans << "\n";
}

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //random_start();
    P[0] = 1;
    rep2(i,1,2000000) P[i] = (P[i-1]*p)%MOD;
    int t = 1;
    cin >> t;
    while(t--) solve();
}

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