Submission #659128

#	Time	Username	Problem	Language	Result	Execution time	Memory
659128		shmad	Lampice (COCI19_lampice)	C++17	42 / 110	5062 ms	28488 KiB

lampice

#pragma GCC optimize("O3", "unroll-loops") // "Ofast" 	
#pragma GCC target("avx2", "bmi", "bmi2", "lzcnt", "popcnt") 

#include <bits/stdc++.h>

//#define int long long
#define vt vector
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define ff first
#define ss second
#define dbg(x) cerr << #x << " = " << x << '\n'
#define bit(x, i) ((x) >> (i) & 1)

using namespace std;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using vvt = vt< vt<ll> >;

const int N = 1e6 + 5, mod = 1e9 + 7, B = 500;
const ll inf = 1e18 + 7, LIM = (1ll << 60);
const ld eps = 1e-6;

int n, ans;
string s;
vt<int> g[N];
vt<char> c;

int get () {
	int res = 0;
	for (int i = 0; i < sz(c); i++) {
		int l = i - 1, r = i + 1;
		while (l >= 0 && r < sz(c)) {
			if (c[l] == c[r]) l--, r++;
			else break;
		}                         
		l++, r--;
		res = max(res, r - l + 1);
		l = i - 1, r = i;
		while (l >= 0 && r < sz(c)) {
			if (c[l] == c[r]) l--, r++;
			else break;
		}
		l++, r--;
		res = max(res, r - l + 1);
	}
	return res;
}

void dfs (int v, int p = -1) {
	c.pb(s[v]);
	bool ok = 0;
	for (auto to: g[v]) {
		if (to != p) {
			ok = 1;
			dfs(to, v);
		}
	}
	if (!ok) ans = max(ans, get());
	c.pop_back();
}

bool pal (vt<char> &c) {
	vt<char> nc = c;
	reverse(all(nc));
	return (c == nc);
}
 
void df (int v, int p = -1) {
	c.pb(s[v]);
	if (pal(c)) ans = max(ans, sz(c));
	for (auto to: g[v]) {
    	if (to != p) df(to, v);
    }
    c.pop_back();
}
 
void solve () {
	cin >> n >> s;
	s = ' ' + s;
	for (int i = 1; i < n; i++) {
		int x, y;
		cin >> x >> y;
		g[x].pb(y);
		g[y].pb(x);
	}
	if (n <= 100) {
		for (int i = 1; i <= n; i++) c.clear(), df(i);
		cout << ans;
	    return;
	}
	for (int i = 1; i <= n; i++) {
	 	if (sz(g[i]) == 1) c.clear(), dfs(i);
	}
	cout << ans;
	cout << '\n';
}

bool testcases = 0;

signed main() {
#ifdef ONLINE_JUDGE
	freopen(".in", "r", stdin);
	freopen(".out", "w", stdout);
#endif
	cin.tie(0) -> sync_with_stdio(0);
	int test = 1;
	if (testcases) cin >> test;
	for (int cs = 1; cs <= test; cs++) {
		solve();
	}
}

• Subtask 1: 17 / 17
• Subtask 2: 25 / 25
• Subtask 3: 0 / 31
• Subtask 4: 0 / 37