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Submission #640436

# Submission time Handle Problem Language Result Execution time Memory
640436 2022-09-14T16:02:06 Z LeonaRaging Lampice (COCI19_lampice) C++14
17 / 110
 5000 ms 17004 KB 
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
 
using namespace __gnu_pbds;
using namespace std;
 
#define fi first
#define se second
#define ll long long
#define pb push_back
#define db(val) "[" #val " = " << (val) << "] "
 
const ll mod = 1e9 + 7;
const int maxn = 1e5 + 4;
const int INF = 1e9;
const ll base = 31;
const int N = 18;
 
int n, len, root, h[maxn], spt[maxn][20];
string s;
vector<int> adj[maxn];
ll Pow[maxn], up[maxn], down[maxn];
gp_hash_table<ll,int> L;
bool flag, used[maxn];
 
ll add(ll a, ll b) {
    a += b;
    return a;
}
 
ll del(ll a, ll b) {
    a -= b;
    return a;
}
 
void pre(int u, int p) {
    if (p) 
        down[u] = add(down[p], (s[u] - 'a' + 1) * Pow[h[u] - 1]);
    if (p) 
        up[u] = add(up[p] * base, s[u] - 'a' + 1);
    L[up[u]]++;
    spt[u][0] = p;
    for (int j = 1; j <= N; j++)
        spt[u][j] = spt[spt[u][j - 1]][j - 1];
    for (int v : adj[u])
        if (v != p && !used[v]) {
            h[v] = h[u] + 1;
            pre(v, u);
        }
}
 
int jump(int u, int k) {
    for (int j = N; j >= 0; j--)
        if (k >> j & 1)
            u = spt[u][j];
    return u;
}
 
void dfs(int u, int p) {
    if (len < h[u] || flag) return;
    int k = len - h[u] - 1, c = jump(u, k);
    if (c && add(up[c], (s[root] - 'a' + 1) * Pow[h[c]]) == 
            add(down[c] * base, (s[root] - 'a' + 1))) {
        if (k == 0)
            return flag = true, void();
        ll val = del(up[u], up[c] * Pow[k]) ;
        if (L.find(val) != L.end()) {
            return flag = true, void();
        }
    }
    for (int v : adj[u])
        if (v != p && !used[v])
            dfs(v, u);
}
 
void reset(int u, int p, int val) {
    L[up[u]] += val;
    if (L[up[u]] == 0)
        L.erase(up[u]);
    for (int v : adj[u])
        if (v != p && !used[v])
            reset(v, u, val);
}
 
void Solve(int c) {
    h[c] = 0;
    up[c] = down[c] = 0;
    L.clear();
    pre(c, 0);
    for (int v : adj[c]) 
        if (!used[v]) {
            if (flag) return;
            reset(v, c, -1);
            dfs(v, c);
            reset(v, c, 1);
        }   
}
 
struct Centroid_Decomposition {
    int sz[maxn];
    int dfs(int u, int p) {
        sz[u] = 1;
        for (int v : adj[u])
            if (!used[v] && v != p)
                sz[u] += dfs(v, u);
        return sz[u];
    }
    int Centroid(int u, int p, int tot) {
        for (int v : adj[u])
            if (!used[v] && v != p && sz[v] > tot / 2)
                return Centroid(v, u, tot);
        return u;
    }
    void build(int u) {
        if (flag) return;
        int c = Centroid(u, 0, dfs(u, 0));
        root = c;
        Solve(c);
        used[c] = 1;
        for (int v : adj[c])
            if (!used[v])
                build(v);
    }
} Cen;
 
bool ok(int m, int sign) {
    flag = false;
    fill(used + 1, used + 1 + n, 0);
    len = 2 * m + sign;
    Cen.build(1);
    return flag;
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    //freopen(".INP", "r", stdin);
    //freopen(".OUT", "w", stdout);
    cin >> n >> s;
    s = ' ' + s;
    Pow[0] = 1;
    for (int i = 1; i < n; i++) {
        int u, v; cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
        for (int i = 1; i <= n; i++) {
            Pow[i] = Pow[i - 1] * base;
        }
    }
    Pow[n] = Pow[n - 1] * base;
    // return cout << ok(4, 1), 0;
    int L = 1, R = n / 2, res = 1;
    while (L <= R) {
        int mid = (L + R) / 2;
        if (ok(mid, 0)) {
            res = max(res, 2 * mid);
            L = mid + 1;
        }
        else R = mid - 1;
    }
    L = res / 2, R = n / 2;
    while (L <= R) {
        int mid = (L + R) / 2;
        if (ok(mid, 1)) {
            res = 2 * mid + 1;
            L = mid + 1;
        }
        else R = mid - 1;
    }
    cout << res;
}

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 2772 KB Output is correct
2 Correct 19 ms 2772 KB Output is correct
3 Correct 67 ms 3096 KB Output is correct
4 Correct 69 ms 3080 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct

Subtask #2
0 / 25.0

# Verdict Execution time Memory Grader output
1 Execution timed out 5065 ms 17004 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
0 / 31.0

# Verdict Execution time Memory Grader output
1 Execution timed out 5066 ms 16832 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #4
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 2772 KB Output is correct
2 Correct 19 ms 2772 KB Output is correct
3 Correct 67 ms 3096 KB Output is correct
4 Correct 69 ms 3080 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct
8 Execution timed out 5065 ms 17004 KB Time limit exceeded
9 Halted 0 ms 0 KB -