Submission #618795

#	Time	Username	Problem	Language	Result	Execution time	Memory
618795		nghiass001	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	102 ms	28680 KiB

palindromic

#include <bits/stdc++.h>
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define FORD(i, r, l) for(int i = (r); i >= (l); --i)
#define REP(i, l, r) for(int i = (l); i < (r); ++i)
#define REPD(i, r, l) for(int i = (r) - 1; i >= (l); --i)
using namespace std;

typedef unsigned long long ull;
const int N = 1e6 + 5;
const ull base = 27;
int t, n;
string s;
ull B[N], H[N];

void Enter() {
    cin >> s;
    n = s.length();
    s = ' ' + s;
}

ull getHash(int l, int r) {
    return H[r] - H[l - 1] * B[r - l + 1];
}

void Process() {
    B[0] = 1;
    FOR(i, 1, n) B[i] = B[i - 1] * base;
    FOR(i, 1, n) H[i] = H[i - 1] * base + s[i] - 'a' + 1;
    int res = (n == 1), len = 0;
    FOR(i, 1, n/2) {
        int j = i;
        while (j <= n/2 && getHash(i, j) != getHash(n - j + 1, n - i + 1)) ++j;
        i = j;
        if (i > n/2) { ++res; break; }
        res += 2;
        if (i * 2 + 1 == n) ++res;
    }
    cout << res << '\n';
}

int main()
{
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    if (fopen("palindromic.inp", "r")) freopen("palindromic.inp", "r", stdin);
    cin >> t;
    while (t--) {
        Enter();
        Process();
    }
}

Compilation message (stderr)

palindromic.cpp: In function 'void Process()':
palindromic.cpp:29:25: warning: unused variable 'len' [-Wunused-variable]
   29 |     int res = (n == 1), len = 0;
      |                         ^~~
palindromic.cpp: In function 'int main()':
palindromic.cpp:44:47: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |     if (fopen("palindromic.inp", "r")) freopen("palindromic.inp", "r", stdin);
      |                                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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