Submission #1076171

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076171		Ejen	Lampice (COCI19_lampice)	C++17	0 / 110	1753 ms	17148 KiB

lampice

#include <bits/stdc++.h>

#define el "\n"
#define fu(i, a, b) for (int i = a; i <= b; ++i)
#define fd(i, a, b) for (int i = a; i >= b; --i)
#define ff first
#define ss second
#define all(v) (v).begin(), (v).end()
#define sz(v) (ll)(v).size()
#define mask(i) (1LL << (i))
#define bit(x, i) ((x) >> (i) & 1)
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
 
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
 
ll Rand(ll l, ll r) {
    return uniform_int_distribution<ll>(l, r) (rng);
}
 
ll last(ll msk)     {return msk & (-msk);}
ll pop_cnt(ll msk)  {return __builtin_popcountll(msk);}
ll ctz(ll msk)      {return __builtin_ctzll(msk);}
ll lg(ll msk)       {return 63 - __builtin_clzll(msk);}
 
template<class T1, class T2> bool minimize(T1 &a, T2 b) {
    return a > b ? a = b, 1 : 0;
}
 
template<class T1, class T2> bool maximize(T1 &a, T2 b) {
    return a < b ? a = b, 1 : 0;
}
 
template<class T> void print(T a) {
    for (auto x : a) cout << x << " ";
    cout << el;
}
 
template<class T> void compress(T &a) {
    sort(all(a));
    a.resize(unique(all(a)) - a.begin());
}
 
const long long N = 5e4 + 27, mod = 1e9 + 7, inf = 2e18, bl = 320, lim = 1e6 + 27;
const pair<ll, ll> base = make_pair(1000, 2000);

ll n, sz;
string s;
ll child[N], h[N];
pair<ll, ll> hashUp[N], hashDown[N], pw[N];
ll up[16][N];
bool del[N];
basic_string<ll> adj[N];
map<pair<ll, ll>, bool> mp;

pair<ll, ll> operator+(pair<ll, ll> x, pair<ll, ll> y) {return make_pair(x.ff + y.ff, x.ss + y.ss);}
pair<ll, ll> operator-(pair<ll, ll> x, pair<ll, ll> y) {return make_pair(x.ff - y.ff, x.ss - y.ss);}
pair<ll, ll> operator*(pair<ll, ll> x, pair<ll, ll> y) {return make_pair(x.ff * y.ff, x.ss * y.ss);}
pair<ll, ll> operator+(pair<ll, ll> x, char c) {return make_pair(x.ff + c, x.ss + c);}
pair<ll, ll> operator*(pair<ll, ll> x, char c) {return make_pair(x.ff * c, x.ss * c);}

void countChild(ll u, ll p) {
    child[u] = 1;
    // cout << u << ' '  << child[u] << el;
    for (ll v : adj[u]) {
        if (v == p || del[v]) continue;
        countChild(v, u);
        child[u] += child[v];
    }
    // cout << child[u] << ' ';
}

ll centroid(ll u, ll p, ll root) {
    for (ll v : adj[u]) {
        if (v == p || del[v] || child[v] <= child[root] / 2) continue;
        return centroid(v, u, root);
    }
    return u;
}

ll lift(ll x, ll k) {
    // if (x == 5) cout << k << el;
    while (k) {
        ll i = ctz(k);
        x = up[i][x];
        k -= last(k);
    }
    return x;
}

void dfs(ll u, ll p) {
    hashUp[u] = hashUp[p] + pw[h[u]] * s[u];
    hashDown[u] = hashDown[p] * base + s[u];
    for (ll v : adj[u]) {
        if (v == up[0][u] || del[v]) continue;
        h[v] = h[u] + 1;
        up[0][v] = u;
        fu(i, 1, lg(h[v])) up[i][v] = up[i - 1][up[i - 1][v]];
        dfs(v, u);
    }
}

void dfsUpdate(ll u, ll len) {
    if (len > h[u]) {
        ll par = lift(u, len - h[u] - 1);
        if (par && hashUp[par] == hashDown[par]) mp[hashDown[u] - hashDown[up[0][par]] * pw[h[u] - h[par] + 1]] = true;
    }
    for (ll v : adj[u]) {
        if (v == up[0][u] || del[v]) continue;
        dfsUpdate(v, len);
    }
}

bool dfsSearch(ll u, ll len) {
    if (mp[hashDown[u]]) return true;
    if (h[u] + 1 == len && hashUp[u] == hashDown[u]) return true;
    for (ll v : adj[u]) {
        if (v == up[0][u] || del[v]) continue;
        if (dfsSearch(v, len)) return true;
    }
    return false;
}

bool check(ll u, ll len) {
    countChild(u, 0);
    ll root = centroid(u, 0, u);
    fu(i, 1, n) fu(j, 0, lg(n)) up[j][i] = 0;
    h[root] = 0;
    dfs(root, 0);
    fu(turn, 0, 1) {
        mp.clear();
        reverse(all(adj[root]));
        for (ll x : adj[root]) {
            if (del[x]) continue;
            if (dfsSearch(x, len)) return true;
            dfsUpdate(x, len);
        }
    }
    del[root] = true;
    for (ll v : adj[root]) {
        if (del[v]) continue;
        return check(v, len);
    }
    return false;
}

signed main() {
//    freopen("bai3.inp", "r", stdin);
//    freopen("bai3.out", "w", stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> s;
    s = ' ' + s;
    sz = sz(s) - 1;
    pw[0] = make_pair(1, 1);
    fu(i, 1, n) pw[i] = pw[i - 1] * base;
    fu(i, 2, n) {
        ll u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    // cout << check(1, 5);
    ll res = 1;
    ll l = 1, r = n / 2;
    while (l <= r) {
        ll mid = (r + l) / 2;
        fu(i, 1, n) del[i] = 0;
        if (check(1, 2 * mid)) {
            res = 2 * mid;
            l = mid + 1;
        }
        else r = mid - 1;
    }
    l = 1, r = n / 2;
    while (l <= r) {
        ll mid = (l + r) / 2;
        fu(i, 1, n) del[i] = 0;
        if (check(1, 2 * mid + 1)) {
            maximize(res, 2 * mid + 1);
            l = mid + 1;
        }
        else r = mid - 1;
    }
    cout << res;

}

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