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Submission #499009

# Submission time Handle Problem Language Result Execution time Memory
499009 2021-12-27T03:08:56 Z hoanghq2004 Lampice (COCI19_lampice) C++14
110 / 110
 4168 ms 12108 KB 
#include <bits/stdc++.h>
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")

using namespace std;

const int N = 5e4 + 10;
const int mod = 1e9 + 7;
const int base = 29;

int n, ti;
char c[N];
int big[N], sz[N], del[N];
vector <int> g[N];

void dfs(int u, int p) {
    big[u] = 0, sz[u] = 1;
    for (auto v: g[u]) {
        if (v == p || del[v] == ti) continue;
        dfs(v, u);
        sz[u] += sz[v];
        if (sz[v] > sz[big[u]]) big[u] = v;
    }
}

int centroid(int u) {
    int num = sz[u] / 2;
    while (sz[big[u]] > num) u = big[u];
    return u;
}

int H[N], power[N];
int rH[N];

int get_hash(int L, int R) {
    return (0LL + H[R] - 1LL * H[L - 1] * power[R - L + 1] + 1LL * mod * mod) % mod;
}

int check(int u, int len) {
    dfs(u, 0);
    u = centroid(u);
    del[u] = ti;
    H[1] = c[u] - 'a' + 1;
    unordered_set <int> s;
    function <void(int, int, int)> add = [&](int u, int p, int d) {
        if (d * 2 > len + 3) return;
        H[d] = (1LL * H[d - 1] * base + c[u] - 'a' + 1) % mod;
        s.insert(H[d]);
        for (auto v: g[u]) {
            if (v == p || del[v] == ti) continue;
            add(v, u, d + 1);
        }
    };
    rH[1] = c[u] - 'a' + 1;
    s.insert(H[1]);
    int ok = 0;
    function <void(int, int, int)> calc = [&](int u, int p, int d) {
        if (d > len || ok) return;
        H[d] = (1LL * H[d - 1] * base + c[u] - 'a' + 1) % mod;
        int rem = len - d + 1;
        rH[d] = (1LL * power[d - 1] * (c[u] - 'a' + 1) + rH[d - 1]) % mod;
        if (d * 2 - len > 0 && rH[d * 2 - len] == H[d * 2 - len]) {
            if (s.find(get_hash(d * 2 - len, d)) != s.end()) {
                ok = 1;
                return;
            }
        }
        for (auto v: g[u]) {
            if (v == p || del[v] == ti) continue;
            calc(v, u, d + 1);
        }
    };
    for (auto v: g[u]) {
        if (del[v] == ti) continue;
        calc(v, u, 2);
        if (ok) return 1;
        add(v, u, 2);
    }
    s.clear();
    reverse(g[u].begin(), g[u].end());
    for (auto v: g[u]) {
        if (del[v] == ti) continue;
        calc(v, u, 2);
        if (ok) return 1;
        add(v, u, 2);
    }
    for (auto v: g[u]) {
        if (del[v] == ti) continue;
        if (check(v, len)) return 1;
    }
    return 0;
}

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> n;
    for (int i = 1; i <= n; ++i) cin >> c[i];
    power[0] = 1;
    for (int i = 1; i <= n; ++i) power[i] = 1LL * power[i - 1] * base % mod;
    for (int i = 1; i < n; ++i) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    int ans = 0;
    int L = 0, R = n / 2;
    while (R - L > 1) {
        int mid = L + R >> 1;
        ++ti;
        if (check(1, mid * 2)) L = mid;
        else R = mid;
    }
    ++ti;
    if (check(1, R * 2)) ans = R * 2;
    else ans = L * 2;
    if (!ans) ans = 1;
    L = 1, R = n / 2 + 1;
    while (R - L > 1) {
        int mid = L + R >> 1;
        ++ti;
        if (check(1, mid * 2 - 1)) L = mid;
        else R = mid;
    }
    ++ti;
    if (check(1, R * 2 - 1)) ans = max(ans, R * 2 - 1);
    else ans = max(ans, L * 2 - 1);
    cout << ans;
}

Compilation message

lampice.cpp:3: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    3 | #pragma GCC optimization ("O3")
      | 
lampice.cpp:4: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    4 | #pragma GCC optimization ("unroll-loops")
      | 
lampice.cpp: In lambda function:
lampice.cpp:61:13: warning: unused variable 'rem' [-Wunused-variable]
   61 |         int rem = len - d + 1;
      |             ^~~
lampice.cpp: In function 'int main()':
lampice.cpp:110:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  110 |         int mid = L + R >> 1;
      |                   ~~^~~
lampice.cpp:121:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  121 |         int mid = L + R >> 1;
      |                   ~~^~~

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 1484 KB Output is correct
2 Correct 12 ms 1588 KB Output is correct
3 Correct 50 ms 1708 KB Output is correct
4 Correct 53 ms 1612 KB Output is correct
5 Correct 1 ms 1484 KB Output is correct
6 Correct 1 ms 1484 KB Output is correct
7 Correct 1 ms 1484 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1985 ms 10192 KB Output is correct
2 Correct 2201 ms 10380 KB Output is correct
3 Correct 1660 ms 11604 KB Output is correct
4 Correct 1886 ms 12108 KB Output is correct
5 Correct 2557 ms 11696 KB Output is correct
6 Correct 274 ms 10140 KB Output is correct

Subtask #3
31.0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 3341 ms 8340 KB Output is correct
2 Correct 4168 ms 8232 KB Output is correct
3 Correct 3992 ms 8380 KB Output is correct
4 Correct 3962 ms 7112 KB Output is correct
5 Correct 3159 ms 7512 KB Output is correct
6 Correct 2903 ms 6936 KB Output is correct

Subtask #4
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 1484 KB Output is correct
2 Correct 12 ms 1588 KB Output is correct
3 Correct 50 ms 1708 KB Output is correct
4 Correct 53 ms 1612 KB Output is correct
5 Correct 1 ms 1484 KB Output is correct
6 Correct 1 ms 1484 KB Output is correct
7 Correct 1 ms 1484 KB Output is correct
8 Correct 1985 ms 10192 KB Output is correct
9 Correct 2201 ms 10380 KB Output is correct
10 Correct 1660 ms 11604 KB Output is correct
11 Correct 1886 ms 12108 KB Output is correct
12 Correct 2557 ms 11696 KB Output is correct
13 Correct 274 ms 10140 KB Output is correct
14 Correct 3341 ms 8340 KB Output is correct
15 Correct 4168 ms 8232 KB Output is correct
16 Correct 3992 ms 8380 KB Output is correct
17 Correct 3962 ms 7112 KB Output is correct
18 Correct 3159 ms 7512 KB Output is correct
19 Correct 2903 ms 6936 KB Output is correct
20 Correct 2225 ms 5068 KB Output is correct
21 Correct 2624 ms 6316 KB Output is correct
22 Correct 3670 ms 7852 KB Output is correct
23 Correct 754 ms 4048 KB Output is correct
24 Correct 3186 ms 6480 KB Output is correct
25 Correct 2784 ms 5560 KB Output is correct
26 Correct 3683 ms 8120 KB Output is correct
27 Correct 3870 ms 8176 KB Output is correct
28 Correct 2348 ms 4164 KB Output is correct
29 Correct 2521 ms 4160 KB Output is correct
30 Correct 2801 ms 6588 KB Output is correct
31 Correct 2689 ms 5024 KB Output is correct
32 Correct 2256 ms 8108 KB Output is correct
33 Correct 2025 ms 6428 KB Output is correct