Submission #1125899

#	Time	Username	Problem	Language	Result	Execution time	Memory
1125899		SoMotThanhXuan	Lampice (COCI19_lampice)	C++20	42 / 110	176 ms	3400 KiB

lampice

#include <bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = (a), _b = (b); i <= _b; ++i)
#define REP(i, a, b) for(int i = (a), _b = (b); i >= _b; --i)
#define mp make_pair
#define all(v) v.begin(), v.end()
#define uni(v) v.erase(unique(all(v)), v.end())
inline bool maximize(int &u, int v){
    if(v > u){
        u = v;
        return true;
    }
    return false;
}
inline bool minimize(int &u, int v){
    if(v < u){
        u = v;
        return true;
    }
    return false;
}
inline bool maximizell(long long &u, long long v){
    if(v > u){
        u = v;
        return true;
    }
    return false;
}
inline bool minimizell(long long &u, long long v){
    if(v < u){
        u = v;
        return true;
    }
    return false;
}
const int mod = 1e9 + 9;
inline int fastPow(int a, int n){
    int res = 1;
    while(n){
        if(n & 1)res = 1ll * res * a * mod;
        a = 1ll * a * a % mod;
        n >>= 1;
    }
    return res;
}
inline void add(int &u, int v){
    u += v;
    if(u >= mod) u -= mod;
}
inline void sub(int &u, int v){
    u -= v;
    if(u < 0) u += mod;
}
const int maxN = 5e4 + 5;
const int inf = 2e9;
const long long infll = 1e18;
char s[maxN];
int n;
vector<int> adj[maxN];
namespace subtask1{
    bool check(){
        return n <= 3000;
    }
    const int maxN = 3e3 + 1;
    const int base = 333;
    int d[maxN];
    int power[maxN];
    int Hash[maxN], revHash[maxN];
    void dfs(int u, int p){
        for(int v : adj[u]){
            if(v != p){
                d[v] = d[u] + 1;
                Hash[v] = (1ll * Hash[u] * base + s[v]) % mod;
                dfs(v, u);
            }
        }
    }
    void dfs2(int u, int p){
        for(int v : adj[u]){
            if(v != p){
                revHash[v] = (1ll * s[v] * power[d[v] - 1] + revHash[u]) % mod;
                dfs2(v, u);
            }
        }
    }
    int answer = 0;
    void query(int centre){
        FOR(i, 1, n)Hash[i] = 0;
        d[centre] = 1;
        Hash[centre] = s[centre];
        revHash[centre] = s[centre];

        dfs(centre, 0);
        dfs2(centre, 0);
        FOR(i, 1, n)if(Hash[i] == revHash[i])maximize(answer, d[i]);
    }

    void solve(){
        power[0] = 1;
        FOR(i, 1, n)power[i] = 1ll * power[i - 1] * base % mod;
        FOR(i, 1, n)query(i);
        cout << answer;
    }
}
namespace subtask2{
    bool check(){
        FOR(i, 1, n){
            for(int v : adj[i]){
                if(abs(v - i) != 1) return false;
            }
        }
        return true;
    }
    int D_odd[maxN], D_even[maxN];
    void Calc_D_odd() {
        int L = 1, R = 0;

        for(int i = 1 ; i <= n ; i++) {
            if(i > R) D_odd[i] = 0;
            else D_odd[i] = min(R - i, D_odd[L + (R - i)]);
            while(i - D_odd[i] - 1 > 0 && i + D_odd[i] + 1 <= n && s[i - D_odd[i] - 1] == s[i + D_odd[i] + 1]) {
                D_odd[i]++;
            }

            if(i + D_odd[i] > R) {
                R = i + D_odd[i];
                L = i - D_odd[i];
            }
        }
    }

    void Calc_D_even() {
        int L = 1, R = 0;

        for(int i = 1 ; i < n ; i++) {
            int j = i + 1;
            if(j > R) D_even[i] = 0;
            else D_even[i] = min(R - j + 1, D_even[L + (R - j)]);
            while(i - D_even[i] > 0 && j + D_even[i] <= n && s[i - D_even[i]] == s[j + D_even[i]]) {
                D_even[i]++;
            }
            if(i + D_even[i] > R) {
                R = i + D_even[i];
                L = j - D_even[i];
            }
        }
    }
    void solve(){
        Calc_D_even();
        Calc_D_odd();
        int answer = 0;
        for (int i = 1; i <= n; i++) {
            answer = max(answer, 2 * D_odd[i] + 1);
            answer = max(answer, 2 * D_even[i]);
        }
        cout << answer;
    }
}
void process(){
    cin >> n;
    FOR(i, 1, n)cin >> s[i];
    FOR(i, 2, n){
        int u, v;
        cin >> u >> v;
        adj[u].emplace_back(v);
        adj[v].emplace_back(u);
    }
    if(subtask1 :: check()) return subtask1 :: solve();
    if(subtask2 :: check()) return subtask2 :: solve();
}
#define NAME ""
int main(){
    if(fopen(NAME".inp", "r")){
        freopen(NAME".inp", "r", stdin);
        freopen(NAME".out", "w", stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int t = 1;
//    cin >> t;
    while(t--)
        process();
//    cerr << '\n' << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << " s\n" ;
    return 0;
}

Compilation message (stderr)

lampice.cpp: In function 'int main()':
lampice.cpp:174:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  174 |         freopen(NAME".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
lampice.cpp:175:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  175 |         freopen(NAME".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 17 / 17
• Subtask 2: 25 / 25
• Subtask 3: 0 / 31
• Subtask 4: 0 / 37