Submission #425176

#	Time	Username	Problem	Language	Result	Execution time	Memory
425176		cpp219	Palindromic Partitions (CEOI17_palindromic)	C++14	100 / 100	143 ms	28684 KiB

palindromic

#pragma GCC optimization "O2"
#pragma GCC optimization "unroll-loop"
#pragma GCC target ("avx2")

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define fs first
#define sc second
using namespace std;
const ll N = 1e6 + 9;
const ll mod = 1e9 + 7;
const ll base = 31;
typedef pair<ll,ll> LL;
string s;
ll T,n,Hash[N],fac[N];

ll GetHash(ll i,ll j){
    return (Hash[j] - Hash[i - 1]*fac[j - i + 1] + mod*mod)%mod;
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    #define task "tst"
    if (fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        //freopen(task".out", "w", stdout);
    }
    fac[0] = 1;
    for (ll i = 1;i < N;i++) fac[i] = (fac[i - 1]*base)%mod;
    cin>>T;
    while(T--){
        cin>>s; n = s.size(); s = " " + s;
        for (ll i = 1;i <= n;i++) Hash[i] = (Hash[i - 1]*base + s[i] - 'a' + 1)%mod;
        ll ans = 0;
        ll L = 1,R = n;
        while(L <= R){
            ll chosen = mod;
            for (ll len = 1;len <= R - L + 1;len++){
                ll p = GetHash(L,L + len - 1),q = GetHash(R - len + 1,R);
                //cout<<len<<" "<<p<<" "<<q<<"\n";
                if (p == q){
                    chosen = len; break;
                }
            }
            ans++;
            if (chosen != R - L + 1) ans++; //cout<<chosen; return 0;
            L = L + chosen; R = R - chosen;
        }
        cout<<ans<<"\n";
    }
}

Compilation message (stderr)

palindromic.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization "O2"
      | 
palindromic.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
palindromic.cpp: In function 'int main()':
palindromic.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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