Submission #924490

#	Time	Username	Problem	Language	Result	Execution time	Memory
924490		Whisper	Lampice (COCI19_lampice)	C++17	110 / 110	1834 ms	15192 KiB

lampice

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;
using T = tuple<ll, ll, ll>;

#define int long long
#define Base 41
#define sz(a) (int)a.size()
#define FOR(i, a, b) for ( int i = a ; i <= b ; i++ )
#define FORD(i, a, b) for (int i = b; i >= a; i --)
#define REP(i, n) for (int i = 0; i < n; ++i)
#define REPD(i, n) for (int i = n - 1; i >= 0; --i)
#define all(x) x.begin() , x.end()
#define pii pair<int , int>
#define fi first
#define se second
#define Lg(x) 31 - __builtin_clz(x)

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)

constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int MAX = 5e4 + 5;
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void setupIO(){
    #define name "Whisper"
    //Phu Trong from Nguyen Tat Thanh High School for gifted student
    srand(time(NULL));
    cin.tie(nullptr)->sync_with_stdio(false); cout.tie(nullptr);
    //freopen(name".inp", "r", stdin);
    //freopen(name".out", "w", stdout);
    cout << fixed << setprecision(10);
}

template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }

template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }
int numNode;
string s;
vector<int> adj[MAX];

int sz[MAX], del[MAX];

void reSubize(int u, int p){
    sz[u] = 1;
    for (auto&v : adj[u]) if(v ^ p){
        if (!del[v]){
            reSubize(v, u); sz[u] += sz[v];
        }
    }
}
int getCentroid(int u, int p, int siz){
    for (auto&v : adj[u]) if(v ^ p){
        if (!del[v] && 2 * sz[v] > siz) return getCentroid(v, u, siz);
    }
    return u;
}

//>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

int l = 0; bool found;
int Pow[MAX];
unordered_map<int, bool> f[MAX];

int maxDepth = 1;
char r;
void dfs(int u, int p, int dep, int up, int down, bool ok){
    if (dep > l) return;
    maximize(maxDepth, dep);
    up = (up * Base + (s[u] - 'a' + 1)) % Mod;
    down = (down + (s[u] - 'a' + 1) * Pow[dep - 1]) % Mod;
    int val = ((down * Pow[l - dep] - up) + Mod) % Mod;
    if (ok) f[dep][val] = 1;
    else{
        if (dep + 1 == l){
            if ((down * Base + (r - 'a' + 1)) % Mod == up){
                found = 1; return;
            }
        }
        if (l > dep)
            if (f[l - dep - 1].count(val)){
                found = 1; return;
            }
    }
    for (auto&v : adj[u]) if(v ^ p){
        if (!del[v]){
            dfs(v, u, dep + 1, up, down, ok);
            if (found) return;
        }
    }
}
void decompose(int root){
    reSubize(root, -1);
    int siz = sz[root];
    root = getCentroid(root, -1, siz);
    r = s[root];
    del[root] = 1;
    maxDepth = 1;
    for (auto&v : adj[root]) if(!del[v]){
        dfs(v, root, 1, s[root] - 'a' + 1, 0, 0);
        if (found) return;
        dfs(v, root, 1, s[root] - 'a' + 1, 0, 1);
    }
    for (int i = 0; i <= maxDepth; ++i) f[i].clear();
    for (auto&v : adj[root]) if(!del[v]){
        decompose(v);
        if (found) return;
    }
}

bool check(int _l){
    l = _l; found = false;
    for (int i = 0; i <= l; ++i) f[i].clear();
    for (int i = 1; i <= numNode; ++i) del[i] = 0;
    decompose(1);
    return found;
}
void Whisper(){
    cin >> numNode >> s;
    s = '@' + s;
    for (int i = 1; i < numNode; ++i){
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    Pow[0] = 1;
    for (int i = 1; i <= numNode; ++i){
        Pow[i] = Pow[i - 1] * Base % Mod;
    }
    int ans = 1;
    for (int i = 0; i < 2; ++i){
        int lo = 0, hi = numNode / 2 + 1;
        while (hi - lo > 1){
            int mid = (lo + hi) >> 1;
            if (check(2 * mid + i)) lo = mid;
            else hi = mid;
        }
        maximize(ans, 2 * lo + i);
    }
    cout << ans;
}


signed main(){
    setupIO();
    int Test = 1;
//    cin >> Test;
    for ( int i = 1 ; i <= Test ; i++ ){
        Whisper();
        if (i < Test) cout << '\n';
    }
}

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