oj.uz

답안 #895871

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
895871 2023-12-31T02:36:41 Z now_or_never Lampice (COCI19_lampice) C++14
110 / 110
 1938 ms 13844 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,bool &found) {
    int c = findCentroid(u, 0, dfsSZ(u, 0)); rem[c] = true;
 
    maxH = 1;
    cc = a[c];
    for (int v: adj[c]) if (!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 (!rem[v]) {
        solve(v,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, 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

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 4696 KB Output is correct
2 Correct 6 ms 4700 KB Output is correct
3 Correct 18 ms 4856 KB Output is correct
4 Correct 19 ms 4696 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 4708 KB Output is correct

Subtask #2
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 841 ms 12616 KB Output is correct
2 Correct 764 ms 12796 KB Output is correct
3 Correct 558 ms 13140 KB Output is correct
4 Correct 640 ms 13432 KB Output is correct
5 Correct 1027 ms 13844 KB Output is correct
6 Correct 132 ms 13056 KB Output is correct

Subtask #3
31.0 / 31.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1444 ms 9816 KB Output is correct
2 Correct 1938 ms 9344 KB Output is correct
3 Correct 1585 ms 10320 KB Output is correct
4 Correct 1557 ms 9632 KB Output is correct
5 Correct 1213 ms 8920 KB Output is correct
6 Correct 1150 ms 8748 KB Output is correct

Subtask #4
37.0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 4696 KB Output is correct
2 Correct 6 ms 4700 KB Output is correct
3 Correct 18 ms 4856 KB Output is correct
4 Correct 19 ms 4696 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 4708 KB Output is correct
8 Correct 841 ms 12616 KB Output is correct
9 Correct 764 ms 12796 KB Output is correct
10 Correct 558 ms 13140 KB Output is correct
11 Correct 640 ms 13432 KB Output is correct
12 Correct 1027 ms 13844 KB Output is correct
13 Correct 132 ms 13056 KB Output is correct
14 Correct 1444 ms 9816 KB Output is correct
15 Correct 1938 ms 9344 KB Output is correct
16 Correct 1585 ms 10320 KB Output is correct
17 Correct 1557 ms 9632 KB Output is correct
18 Correct 1213 ms 8920 KB Output is correct
19 Correct 1150 ms 8748 KB Output is correct
20 Correct 950 ms 7208 KB Output is correct
21 Correct 1085 ms 7972 KB Output is correct
22 Correct 1547 ms 8352 KB Output is correct
23 Correct 355 ms 6492 KB Output is correct
24 Correct 1302 ms 8308 KB Output is correct
25 Correct 1291 ms 7764 KB Output is correct
26 Correct 1515 ms 10064 KB Output is correct
27 Correct 1590 ms 8540 KB Output is correct
28 Correct 1081 ms 6736 KB Output is correct
29 Correct 1117 ms 6744 KB Output is correct
30 Correct 1216 ms 9140 KB Output is correct
31 Correct 1074 ms 7512 KB Output is correct
32 Correct 1006 ms 10076 KB Output is correct
33 Correct 766 ms 8120 KB Output is correct