Submission #1108809

#	Time	Username	Problem	Language	Result	Execution time	Memory
1108809		koukirocks	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	159 ms	28292 KiB

palindromic

#include <bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0); cin.tie(0)
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx,avx2")
//#pragma GCC target("popcnt")
 
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
 
const ll MAX=2e5+10,P=1e9+7;
const ll INF=0x3f3f3f3f,oo=0x3f3f3f3f3f3f3f3f;
const ldb eps=1e-6;
const ldb PI=acos(-1.0);
const int dir[4][2]={{0,1},{0,-1},{1,0},{-1,0}};
template<typename T>
using vvector = vector<vector<T>>;

ll pw(ll a,ll b) {
    ll ans=1;
    ll now=a;
    while (b) {
        if (b&1) {
            ans*=now;
            ans%=P;
        }
        now*=now;
        now%=P;
        b>>=1;
    }
    return ans;
}

struct Hash {
    string s;
    ll n;
    ll x;
    vector<ll> pre,inv;
    Hash(string _s,int x):s(_s),n(s.size()-1),x(x) {
        pre.resize(n+1);
        inv.resize(n+1);
        ll now=1;
        inv[0]=1;
        inv[1]=pw(x,P-2);
        for (int i=1;i<=n;i++) {
            now = (now*x)%P;
            inv[i]=inv[i-1]*inv[1];
            inv[i]%=P;
            pre[i]=pre[i-1]+s[i]*now;
            pre[i]%=P;
        }
    }
    ll query(ll a,ll b) {
        return (pre[b]-pre[a-1]+P)%P*inv[a-1]%P;
    }
};

void solve() {
    string s;
    cin>>s;
    int n = s.size();
    s = '-'+s;
    Hash h(s,83);
    int now=1;
    int ans=0;
    for (int i=1;2*i<=n;i++) {
        if (h.query(now,i)==h.query(n-i+1,n-now+1)) {
            ans+=2;
            now=i+1;
        }
    }
    cout<<ans+(now<=n-now+1)<<"\n";
}

int main() {
    speed;
    int t;
    cin>>t;
    while (t--) {
        solve();
    }
    return 0;
}

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