oj.uz

답안 #881868

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
881868 2023-12-02T06:20:22 Z chanhchuong123 Lampice (COCI19_lampice) C++14
17 / 110
 5000 ms 11352 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 MAX = 50005;
int n, k;
char a[MAX];
int sz[MAX];
bool rem[MAX];
vector<int> adj[MAX];

const int MOD = 1e9 + 7;
const int BASE = 29;
int pw[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 (2 * sz[v] > n)
            return findCentroid(v, u, n);
    }
    return u;
}

int h[MAX];
int maxHigh;
int hashU[MAX];
int hashD[MAX];
int value[MAX];
int nNode, node[MAX];
map<int, bool> mp[MAX];

void add(int u, int p, bool &found) {
    h[u] = h[p] + 1;
    if (h[u] + 1 > k) return;
    maxHigh = max(maxHigh, h[u]);
    hashU[u] = (1LL * hashU[p] * BASE + (a[u] - 'a' + 1)) % MOD;
    hashD[u] = (hashD[p] + 1LL * pw[h[u]] * (a[u] - 'a' + 1)) % MOD;
    int need = (1LL * pw[k - h[u] - 1] * hashD[u] - hashU[u] + MOD) % MOD;
    if (mp[k - h[u] - 1].find(need) != mp[k - h[u] - 1].end()) {
        found = true;
        return;
    }
    if (h[u] + 1 == k && hashD[u] == (hashU[u] + 1LL * pw[h[u]] * (a[u] - 'a' + 1)) % MOD) {
        found = true;
        return;
    }
    node[++nNode] = u; value[u] = need;
    for (int v: adj[u]) if (v != p && !rem[v]) {
        add(v, u, found);
        if (found) return;
    }
}

void solve(int u, int p, bool &found) {
    int n = dfsSZ(u, p), c = findCentroid(u, p, n); rem[c] = true;

    h[c] = 0;
    nNode = 0;
    hashU[c] = 0;
    hashD[c] = a[c] - 'a' + 1;
    for (int v: adj[c]) if (v != p && !rem[v]) {
        add(v, c, found);
        if (found) return;
        while (nNode > 1) {
            int u = node[nNode--];
            mp[h[u]][value[u]] = 1;
        }
    }
    for (int i = 0; i <= maxHigh; ++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) {
    memset(rem, false, sizeof rem);
    bool found = false; k = x;
    solve(1, 0, 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 >> (a + 1); pw[0] = 1; for (int i = 1; i <= n; ++i) pw[i] = 1LL * pw[i - 1] * BASE % MOD;
    for (int i = 1; i <= n - 1; ++i) {
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    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:114:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  114 |             int mid = l + r >> 1;
      |                       ~~^~~
lampice.cpp:100:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  100 |   freopen(task".inp", "r",  stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
lampice.cpp:101:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |   freopen(task".out", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
17.0 / 17.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 5212 KB Output is correct
2 Correct 5 ms 5212 KB Output is correct
3 Correct 23 ms 5348 KB Output is correct
4 Correct 20 ms 5208 KB Output is correct
5 Correct 1 ms 4952 KB Output is correct
6 Correct 1 ms 4956 KB Output is correct
7 Correct 1 ms 4956 KB Output is correct

Subtask #2
0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 5018 ms 11352 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 5048 ms 10076 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #4
0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 5212 KB Output is correct
2 Correct 5 ms 5212 KB Output is correct
3 Correct 23 ms 5348 KB Output is correct
4 Correct 20 ms 5208 KB Output is correct
5 Correct 1 ms 4952 KB Output is correct
6 Correct 1 ms 4956 KB Output is correct
7 Correct 1 ms 4956 KB Output is correct
8 Execution timed out 5018 ms 11352 KB Time limit exceeded
9 Halted 0 ms 0 KB -