oj.uz

답안 #546628

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
546628 2022-04-07T22:27:57 Z Olympia Lampice (COCI19_lampice) C++17
17 / 110
 5000 ms 11912 KB 
#include <cmath>
#include <iostream>
#include <set>
#include <climits>
#include <cstdio>
#include <algorithm>
#include <cassert>
#include <unordered_set>
#include <string>
#include <vector>
#include <iomanip>
#include <unordered_map>
#include <type_traits>
#include <string>
#include <queue>
#include <map>

using namespace std;

const int MOD = 1e9 + 9;
const int M = 1e9 + 9;
const int BASE = 293;
const int inv = 706484648;

struct modint {
    modint() : n(0) {}
    template <class T> modint(T n) { n %= M; if (n < 0) n += M; this->n = n; }

    modint & operator+=(const modint &r) { n += r.n; if (n >= M) n -= M; return *this; }
    modint & operator-=(const modint &r) { n -= r.n; if (n < 0) n += M; return *this; }
    modint & operator*=(const modint &r) { n = (int) ((long long) n * r.n % M); return *this; }

    modint & operator--() { if (--n == -1) n = M - 1; return *this; }
    modint & operator++() { if (++n == M) n = 0; return *this; }
    modint operator--(int) { modint t = *this; --*this; return t; }
    modint operator++(int) { modint t = *this; ++*this; return t; }

    modint operator-() const { return 0 - *this; }
    modint operator+() const { return *this; }

    modint pow(long long k = M - 2) const {
        modint f = *this, p = 1;
        while (k > 0) {
            if (k % 2 == 1) f *= p;
            p *= p, k /= 2;
        }
        return f;
    }

    int mod() const { return M; }

    friend modint operator+(modint l, const modint &r) { return l += r; }
    friend modint operator-(modint l, const modint &r) { return l -= r; }
    friend modint operator*(modint l, const modint &r) { return l *= r; }

    friend bool operator==(const modint &l, const modint &r) { return l.n == r.n; }
    friend bool operator!=(const modint &l, const modint &r) { return l.n != r.n; }

    friend ostream & operator<<(ostream &out, const modint &r) { return out << r.n; }

    int n;
};


class Tree {
public:
    vector<int> sub, depth, parent;
    vector<modint> dp1, dp2;
    vector<bool> hasVisited;
    vector<int> adj[(int)5e4];
    vector<int64_t> powr, ipowr;
    int dp[(int)5e4][17];
    string s;
    int sz;
    int dfs1 (int curNode, int prevNode) {
        sub[curNode] = 1;
        for (int i: adj[curNode]) if (!hasVisited[i] && i != prevNode) sub[curNode] += dfs1(i, curNode);
        return (sz = sub[curNode]);
    }
    int get_centroid (int curNode, int prevNode) {
        for (int i: adj[curNode]) if (!hasVisited[i] && i != prevNode && sub[i] > sz/2) return get_centroid(i, curNode);
        return curNode;
    }
    int max_len; int fine = 0;
    void fill (int curNode, int prevNode, int d, modint val1, modint val2) {
        dp1[curNode] = val1 = BASE * val1 + s[curNode];
        dp2[curNode] = val2 = powr[d] * s[curNode] + val2;
        fine += (dp1[curNode] == dp2[curNode] && d + 1 == max_len);
        dp[curNode][0] = prevNode;
        for (int i = 1; i < 17; i++) {
            dp[curNode][i] = dp[dp[curNode][i - 1]][i - 1];
        }
        depth[curNode] = d;
        parent[curNode] = prevNode;
        for (int i: adj[curNode]) {
            if (!hasVisited[i] && i != prevNode) {
                fill(i, curNode, d + 1, val1, val2);
            }
        }
    }

    int64_t go_up (int l, int d) {
        while (d) {
            l = dp[l][(int)log2(d & -d)];
            d -= (d & -d);
        }
        return l;
    }

    int centroid;
    int64_t get (int l, int r) {
        if (depth[l] < depth[r]) {
            return (dp1[r] - (powr[depth[r] - depth[l] + 1] * dp1[parent[l]])).n;
        } else {
            return ((dp2[l] - dp2[parent[r]]) * (ipowr[depth[r]])).n;
        }
    }

    unordered_set<int> m1;
    vector<int> to_do;
    void dfs (int curNode, int prevNode) {
        if (depth[curNode] + 1 >= max_len) {
            return;
        }
        to_do.push_back(dp1[curNode].n);
        if (2 * depth[curNode] + 1 >= max_len) {
            int x = go_up(curNode, max_len - depth[curNode] - 2);
            if (dp1[parent[x]] == dp2[parent[x]]) {
                if (m1.count((get(x, curNode) + powr[max_len - depth[curNode] - 1] * s[centroid]) % MOD)) {
                    fine ++;
                    return;
                }
            }
        }
        for (int i: adj[curNode]) {
            if (i != prevNode && !hasVisited[i]) {
                dfs (i, curNode);
            }
        }
    }

    bool solve (int curNode) {
        dfs1(curNode, curNode);
        centroid = get_centroid(curNode, curNode);
        hasVisited[centroid] = true;
        depth[centroid] = 0;
        for (int i = 0; i < 17; i++) dp[centroid][i] = centroid;
        dp1[centroid] = s[centroid], dp2[centroid] = s[centroid];
        fine += (max_len == 1);
        for (int i: adj[centroid]) {
            if (!hasVisited[i]) {
                fill(i, centroid, 1, s[centroid], s[centroid]);
            }
        }
        m1.clear();
        for (int i: adj[centroid]) {
            if (!hasVisited[i]) {
                dfs (i, centroid);
                for (int j: to_do) m1.insert(j);
                to_do.clear();
            }
        }
        if (fine) return true;
        reverse(adj[centroid].begin(), adj[centroid].end());
        m1.clear();
        for (int i: adj[centroid]) {
            if (!hasVisited[i]) {
                dfs (i, centroid);
                for (int j: to_do) m1.insert(j);
                to_do.clear();
            }
        }
        if (fine) return true;
        for (int i: adj[centroid]) {
            if (!hasVisited[i]) {
                if (solve(i)) {
                    return true;
                }
            }
        }
        return false;
    }
    Tree (int n) {
        sub.resize(n), hasVisited.assign(n, false); powr.push_back(1); for (int i = 0; i <= n + 5; i++) powr.push_back(powr.back() * BASE), powr.back() %= MOD;
        ipowr.push_back(1); for (int i = 0; i <= n + 5; i++) ipowr.push_back(ipowr.back() * inv), powr.back() %= MOD;
        parent.resize(n), depth.resize(n), dp1.resize(n), dp2.resize(n);
    }
};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n; cin >> n;
    string s; cin >> s;
    Tree myTree(n);
    for (int i = 0; i < n - 1; i++) {
        int u, v;
        cin >> u >> v;
        u--, v--;
        myTree.adj[u].push_back(v), myTree.adj[v].push_back(u);
    }
    myTree.s = s;
    int myMax = 0;
    int l = 0;
    int r = s.length()/2;
    while (l != r) {
        int m = (l + r + 1)/2;
        myTree.max_len = 2 * m; myTree.fine = 0; myTree.hasVisited.assign(n, false);
        myTree.solve(0);
        if (myTree.fine) {
            l = m;
        } else {
            r = m - 1;
        }
    }
    myMax = max(myMax, 2 * l);
    l = 0;
    r = s.length()/2;
    while (l != r) {
        int m = (l + r + 1)/2;
        myTree.max_len = 2 * m + 1; myTree.fine = 0; myTree.hasVisited.assign(n, false);
        myTree.solve(0);
        if (myTree.fine) {
            l = m;
        } else {
            r = m - 1;
        }
    }
    myMax = max(myMax, 2 * l + 1);
    cout << myMax;
    //cout << inv(BASE) << '\n';
}

Subtask #1
17.0 / 17.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 4820 KB Output is correct
2 Correct 15 ms 4820 KB Output is correct
3 Correct 68 ms 4948 KB Output is correct
4 Correct 54 ms 5004 KB Output is correct
5 Correct 3 ms 4692 KB Output is correct
6 Correct 2 ms 4692 KB Output is correct
7 Correct 2 ms 4692 KB Output is correct

Subtask #2
0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 5030 ms 11912 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
0 / 31.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 5060 ms 11216 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #4
0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 4820 KB Output is correct
2 Correct 15 ms 4820 KB Output is correct
3 Correct 68 ms 4948 KB Output is correct
4 Correct 54 ms 5004 KB Output is correct
5 Correct 3 ms 4692 KB Output is correct
6 Correct 2 ms 4692 KB Output is correct
7 Correct 2 ms 4692 KB Output is correct
8 Execution timed out 5030 ms 11912 KB Time limit exceeded
9 Halted 0 ms 0 KB -