Submission #65189

#	Time	Username	Problem	Language	Result	Execution time	Memory
65189		qkxwsm	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	297 ms	63008 KiB

palindromic

/*
PROG: source
LANG: C++11
    _____
  .'     '.
 /  0   0  \
|     ^     |
|  \     /  |
 \  '---'  /
  '._____.'
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

struct chash
{
        int operator()(int x) const
        {
                x ^= (x >> 20) ^ (x >> 12);
                return x ^ (x >> 7) ^ (x >> 4);
        }
        int operator()(long long x) const
        {
                return x ^ (x >> 32);
        }
};

template<typename T> using orderedset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using hashtable = gp_hash_table<T, U, chash>;

template<class T>
void readi(T &x)
{
	T input = 0;
	bool negative = false;
	char c = ' ';
	while (c < '-')
        {
		c = getchar();
	}
	if (c == '-')
	{
		negative = true;
		c = getchar();
	}
	while (c >= '0')
	{
		input = input * 10 + (c - '0');
		c = getchar();
	}
	if (negative)
	{
		input = -input;
	}
	x = input;
}
template<class T>
void printi(T output)
{
	if (output == 0)
	{
		putchar('0');
		return;
	}
	if (output < 0)
	{
		putchar('-');
		output = -output;
	}
	int aout[20];
	int ilen = 0;
	while(output)
	{
		aout[ilen] = ((output % 10));
		output /= 10;
		ilen++;
	}
	for (int i = ilen - 1; i >= 0; i--)
	{
		putchar(aout[i] + '0');
	}
	return;
}
template<class T>
void ckmin(T &a, T b)
{
	a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
	a = max(a, b);
}
template<class T, class U>
T normalize(T x, U mod = 1000000007)
{
	return (((x % mod) + mod) % mod);
}
long long randomizell(long long mod)
{
	return ((1ll << 45) * rand() + (1ll << 30) * rand() + (1ll << 15) * rand() + rand()) % mod;
}
int randomize(int mod)
{
	return ((1ll << 15) * rand() + rand()) % mod;
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-10;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 1000013

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;

int TC;
int N;
int arr[MAXN];
pll pw[MAXN];
pll hashval[MAXN];
int ans;

pll gethash(int L, int R)
{
        pll res;
        res.fi = (hashval[R + 1].fi - hashval[L].fi * pw[R - L + 1].fi) % INF;
        if (res.fi < 0) res.fi += INF;
        res.se = (hashval[R + 1].se - hashval[L].se * pw[R - L + 1].se) % BIG;
        if (res.se < 0) res.se += BIG;
        return res;
}

int32_t main()
{
	ios_base::sync_with_stdio(0);
	srand(time(0));
	//	cout << fixed << setprecision(10);
	//	cerr << fixed << setprecision(10);
	if (fopen("input.in", "r"))
	{
		freopen ("input.in", "r", stdin);
		freopen ("output.out", "w", stdout);
	}
        pw[0] = {1, 1};
        for (int i = 1; i < MAXN; i++)
        {
                pw[i].fi = (pw[i - 1].fi * CO) % INF;
                pw[i].se = (pw[i - 1].se * CO) % BIG;
        }
        cin >> TC;
        while(TC--)
        {
                ans = 0;
                string temps;
                cin >> temps;
                N = temps.length();
                for (int i = 0; i < N; i++)
                {
                        arr[i] = temps[i] - 'a' + 1;
                }
                hashval[0] = {0, 0};
                for (int i = 0; i < N; i++)
                {
                        hashval[i + 1].fi = (hashval[i].fi * CO + arr[i]) % INF;
                        hashval[i + 1].se = (hashval[i].se * CO + arr[i]) % BIG;
                }
                // cerr << gethash(0, 1).fi << ' ' << gethash(4, 5).fi << endl;
                int lt = 0, rt = N - 1;
                for (int i = 0; ; i++)
                {
                        // cerr << lt << ' ' << i << ' ' << N - 1 - i << ' ' << rt << endl;
                        if (gethash(lt, i) == gethash(N - 1 - i, rt))
                        {
                                if (i >= N - 1 - i)
                                {
                                        ans++;
                                }
                                else
                                {
                                        ans += 2;
                                }
                                lt = i + 1;
                                rt = N - 2 - i;
                                if (lt > rt) break;
                        }
                        if (i == N - 1 - i || i + 1 == N - 1 - i)
                        {
                                ans++;
                                break;
                        }
                }
                cout << ans << '\n';
        }
	//	cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
	return 0;
}

Compilation message (stderr)

palindromic.cpp: In function 'int32_t main()':
palindromic.cpp:168:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen ("input.in", "r", stdin);
   ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
palindromic.cpp:169:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen ("output.out", "w", stdout);
   ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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