oj.uz

Submission #546649

# Submission time Handle Problem Language Result Execution time Memory
546649 2022-04-07T23:26:27 Z Olympia Lampice (COCI19_lampice) C++14
42 / 110
 4711 ms 14504 KB 
#include <cmath>
#include <iostream>
#include <set>
#include <climits>
#include <cstdio>
#include <algorithm>
#include <cassert>
#include <string>
#include <vector>
#include <iomanip>
#include <chrono>
#include <unordered_map>
#include <type_traits>
#include <string>
#include <queue>
#include <map>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/assoc_container.hpp>


using namespace std;
using namespace __gnu_pbds;


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

const int RANDOM = chrono::high_resolution_clock::now().time_since_epoch().count();
struct chash {
    int operator()(int x) const { return x ^ RANDOM; }
};


class Tree {
public:
    vector<int> sub, depth, parent;
    vector<int64_t> 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, int64_t val1, int64_t val2) {
        dp1[curNode] = val1 = (BASE * val1 + s[curNode]) % MOD;
        dp2[curNode] = val2 = (powr[d] * s[curNode] + val2) % MOD;
        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;
    __gnu_pbds::gp_hash_table<int, bool, chash> m1;
  
    vector<int> to_do;
    void dfs (int curNode, int prevNode) {
        if (depth[curNode] + 1 >= max_len) {
            return;
        }
        to_do.push_back(dp1[curNode]);
        for (int i: adj[curNode]) {
            if (i != prevNode && !hasVisited[i]) {
                dfs (i, curNode);
            }
        }
        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.find(((dp1[curNode] - (powr[max_len - depth[curNode] - 1] * dp1[parent[x]]) % MOD + MOD) % MOD + powr[max_len - depth[curNode] - 1] * s[centroid]) % MOD) != m1.end()) {
                    fine ++;
                    return;
                }
            }
        }
    }

    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[j] = 1;
                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[j] = 1;
                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;
}

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 4820 KB Output is correct
2 Correct 13 ms 4908 KB Output is correct
3 Correct 47 ms 4948 KB Output is correct
4 Correct 53 ms 4948 KB Output is correct
5 Correct 2 ms 4820 KB Output is correct
6 Correct 2 ms 4804 KB Output is correct
7 Correct 2 ms 4692 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 2774 ms 13336 KB Output is correct
2 Correct 2226 ms 13680 KB Output is correct
3 Correct 1419 ms 13644 KB Output is correct
4 Correct 1726 ms 14208 KB Output is correct
5 Correct 2652 ms 14504 KB Output is correct
6 Correct 314 ms 12652 KB Output is correct

Subtask #3
0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 4636 ms 12648 KB Output is correct
2 Correct 4711 ms 12660 KB Output is correct
3 Correct 4213 ms 12552 KB Output is correct
4 Incorrect 3371 ms 11400 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #4
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 4820 KB Output is correct
2 Correct 13 ms 4908 KB Output is correct
3 Correct 47 ms 4948 KB Output is correct
4 Correct 53 ms 4948 KB Output is correct
5 Correct 2 ms 4820 KB Output is correct
6 Correct 2 ms 4804 KB Output is correct
7 Correct 2 ms 4692 KB Output is correct
8 Correct 2774 ms 13336 KB Output is correct
9 Correct 2226 ms 13680 KB Output is correct
10 Correct 1419 ms 13644 KB Output is correct
11 Correct 1726 ms 14208 KB Output is correct
12 Correct 2652 ms 14504 KB Output is correct
13 Correct 314 ms 12652 KB Output is correct
14 Correct 4636 ms 12648 KB Output is correct
15 Correct 4711 ms 12660 KB Output is correct
16 Correct 4213 ms 12552 KB Output is correct
17 Incorrect 3371 ms 11400 KB Output isn't correct
18 Halted 0 ms 0 KB -