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Submission #895869

# Submission time Handle Problem Language Result Execution time Memory
895869 2023-12-31T02:26:43 Z now_or_never Lampice (COCI19_lampice) C++14
110 / 110
 1774 ms 14456 KB 
#include <bits/stdc++.h>
using namespace std;
#define task ""
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
 
const int MOD = 1e9 + 7;
const int MAX = 50005;
const int BASE = 256;
int n;
int len;
char cc;
int maxH;
int sz[MAX];
char a[MAX];
int pw[MAX];
bool rem[MAX];
vector<int> adj[MAX];
unordered_map<int, bool> mp[MAX];
 
int dfsSZ(int u, int p) {
    sz[u] = 1;
    for (int v: adj[u]) if (v != p && !rem[v]) {
        sz[u] += dfsSZ(v, u);
    }
    return sz[u];
}
 
int findCentroid(int u, int p, int n) {
    for (int v: adj[u]) if (v != p && !rem[v]) {
        if ((sz[v] << 1) > n)
            return findCentroid(v, u, n);
    }
    return u;
}
 
void dfs(int u, int p, bool upd, int h, int up, int dw, bool &found) {
    up = (1LL * up * BASE + (a[u] - 'a' + 1)) % MOD; dw = (dw + 1LL * pw[h - 1] * (a[u] - 'a' + 1)) % MOD;
    int value = (1LL * pw[len - h] * dw - up + MOD) % MOD;
    if (upd) mp[h][value] = true;
    else {
        if (h + 1 == len && (1LL * dw * BASE + (cc - 'a' + 1)) % MOD == up) {
            found = true;
            return;
        }
        if (len > h && mp[len - h - 1].find(value) != mp[len - h - 1].end()) {
            found = true;
            return;
        }
    }
    if (h < len) {
        for (int v: adj[u]) if (v != p && !rem[v]) {
            dfs(v, u, upd, h + 1, up, dw, found);
            maxH = max(maxH, h + 1);
            if (found) return;
        }
    }
}
 
void solve(int u, int p, bool &found) {
    int c = findCentroid(u, p, dfsSZ(u, p)); rem[c] = true;
 
    maxH = 1;
    cc = a[c];
    for (int v: adj[c]) if (v != p && !rem[v]) {
        dfs(v, c, 0, 1, a[c] - 'a' + 1, 0, found);
        if (found) return;
        dfs(v, c, 1, 1, a[c] - 'a' + 1, 0, found);
    }
    for (int i = 0; i <= maxH; ++i) {
        mp[i].clear();
    }
 
    for (int v: adj[c]) if (v != p && !rem[v]) {
        solve(v, c, found);
        if (found) return;
    }
}
 
bool ok(int x) {
    for (int i = 0; i <= n; ++i) mp[i].clear();
    memset(rem, false, sizeof rem);
    bool found = false; len = x;
    solve(1, -1, found);
    return found;
}
 
int main() {
	ios_base::sync_with_stdio(false); cin.tie(nullptr);
 
	if (fopen(task".inp", "r")) {
		freopen(task".inp", "r",  stdin);
		freopen(task".out", "w", stdout);
	}
 
    cin >> n;
    cin >> (a + 1);
    for (int i = 1; i < n; ++i) {
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    pw[0] = 1; for (int i = 1; i <= n; ++i) {
      pw[i] = 1LL * pw[i - 1] * BASE % MOD;
    }
    int ans = 1;
    for (int i = 0; i < 2; ++i) {
        int l = 0, r = n / 2 + 1;
        while (r - l > 1) {
            int mid = l + r >> 1;
            if (ok(i + 2 * mid)) l = mid; else r = mid;
        }
        ans = max(ans, i + 2 * l);
    }
    cout << ans;
	return 0;
}

Compilation message

lampice.cpp: In function 'int main()':
lampice.cpp:110:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  110 |             int mid = l + r >> 1;
      |                       ~~^~~
lampice.cpp:92:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |   freopen(task".inp", "r",  stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
lampice.cpp:93:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |   freopen(task".out", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4700 KB Output is correct
2 Correct 6 ms 4796 KB Output is correct
3 Correct 22 ms 5056 KB Output is correct
4 Correct 19 ms 4700 KB Output is correct
5 Correct 1 ms 4700 KB Output is correct
6 Correct 1 ms 4700 KB Output is correct
7 Correct 1 ms 4700 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 808 ms 12616 KB Output is correct
2 Correct 732 ms 13340 KB Output is correct
3 Correct 510 ms 13592 KB Output is correct
4 Correct 652 ms 14028 KB Output is correct
5 Correct 1066 ms 14456 KB Output is correct
6 Correct 152 ms 13660 KB Output is correct

Subtask #3
31.0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 1406 ms 9980 KB Output is correct
2 Correct 1774 ms 9936 KB Output is correct
3 Correct 1535 ms 10660 KB Output is correct
4 Correct 1529 ms 10240 KB Output is correct
5 Correct 1174 ms 9560 KB Output is correct
6 Correct 1121 ms 9248 KB Output is correct

Subtask #4
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4700 KB Output is correct
2 Correct 6 ms 4796 KB Output is correct
3 Correct 22 ms 5056 KB Output is correct
4 Correct 19 ms 4700 KB Output is correct
5 Correct 1 ms 4700 KB Output is correct
6 Correct 1 ms 4700 KB Output is correct
7 Correct 1 ms 4700 KB Output is correct
8 Correct 808 ms 12616 KB Output is correct
9 Correct 732 ms 13340 KB Output is correct
10 Correct 510 ms 13592 KB Output is correct
11 Correct 652 ms 14028 KB Output is correct
12 Correct 1066 ms 14456 KB Output is correct
13 Correct 152 ms 13660 KB Output is correct
14 Correct 1406 ms 9980 KB Output is correct
15 Correct 1774 ms 9936 KB Output is correct
16 Correct 1535 ms 10660 KB Output is correct
17 Correct 1529 ms 10240 KB Output is correct
18 Correct 1174 ms 9560 KB Output is correct
19 Correct 1121 ms 9248 KB Output is correct
20 Correct 908 ms 8020 KB Output is correct
21 Correct 1051 ms 8532 KB Output is correct
22 Correct 1520 ms 9096 KB Output is correct
23 Correct 379 ms 7252 KB Output is correct
24 Correct 1251 ms 9040 KB Output is correct
25 Correct 1211 ms 8276 KB Output is correct
26 Correct 1535 ms 10452 KB Output is correct
27 Correct 1565 ms 9160 KB Output is correct
28 Correct 1012 ms 7260 KB Output is correct
29 Correct 1096 ms 7308 KB Output is correct
30 Correct 1189 ms 9748 KB Output is correct
31 Correct 1014 ms 8232 KB Output is correct
32 Correct 967 ms 10888 KB Output is correct
33 Correct 742 ms 8884 KB Output is correct