Submission #1125902

#	Time	Username	Problem	Language	Result	Execution time	Memory
1125902		TVSown	Lampice (COCI19_lampice)	C++20	48 / 110	2240 ms	12480 KiB

lampice

///*** Sown_Vipro ***///
/// ->TUYEN QUOC GIA<- ///

#include<bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("popcnt")
#define F first
#define S second
#define pb push_back
#define pi pair<int, int>
#define pii pair<int, pair<int, int> >
#define all(a) a.begin(), a.end()
#define FOR(i, a, b) for(int i = a; i <= b; ++i)
#define REP(i, a, b) for(int i = a; i >= b; --i)
#define inp(name) if(fopen(name, "r")) freopen(name, "r", stdin);
#define out(name) if(fopen(name, "w")) freopen(name, "w", stdout);
void maxi(int &x, int y){ if(x < y) x = y; }
const int N = 50000 + 5, MAX = 1e6, oo = 1e9 + 5, MOD = 1e9 + 7, base = 311;
int n, ans, maxDepth;
int s[N], del[N], pw[N];
string str;
vector<int> e[N];
map<int, bool> f[N];

void count_child(int u, int p){
    s[u] = 1;
    for(int v : e[u]){
        if(v != p && !del[v]){
            count_child(v, u);
            s[u] += s[v];
        }
    }
}

int find_centroid(int u, int p, int n){
    for(int v : e[u]){
        if(v != p && !del[v] && s[v] > n) return find_centroid(v, u, n);
    }
    return u;
}

vector<pi> b;

bool dfs(int u, int p, int k, int h, int up, int down){
    if(k < h) return false;
    maxi(maxDepth, h);
    down = (1ll * down * base + str[u]) % MOD;
    up = (1ll * str[u] * pw[h - 1] + up) % MOD;
    int x = (1ll * up * pw[k - h] - down + MOD) % MOD;

    if(f[k - h].find(x) != f[k - h].end()) return true;

    if(!p) b.clear();
    for(int v : e[u]){
        if(v != p && !del[v]){
            if(dfs(v, u, k, h + 1, up, down)) return true;
        }
    }
    b.pb({h - 1, x});
    if(!p){
        for(auto [h, x] : b) f[h][x] = true;
    }

    return false;
}

bool build(int u, int k){
    count_child(u, 0);
    int cen = find_centroid(u, 0, s[u] / 2);
    del[cen] = 1;
    int x = (-str[cen] + MOD) % MOD;
    f[0][x] = 1;
    for(int v : e[cen]){
        if(del[v]) continue;

        if(dfs(v, 0, k, 2, 0, str[cen])){
            FOR(d, 0, maxDepth) f[d].clear();
            maxDepth = 0;
            return true;
        }
    }

    FOR(d, 0, maxDepth) f[d].clear();
    maxDepth = 0;

    for(int v : e[cen]){
        if(!del[v]) if(build(v, k)) return true;
    }
    return false;
}

void solve(){
    cin >> n;
    cin >> str;
    str = "#" + str;
    FOR(i, 2, n){
        int u, v; cin >> u >> v;
        e[u].pb(v);
        e[v].pb(u);
    }
    pw[0] = 1;
    FOR(i, 1, n) pw[i] = (1ll * pw[i - 1] * base) % MOD;


    int l = 1, r = n; ans = 1;
    while(l <= r){
        int mid = (l + r) / 2;
        FOR(u, 1, n) del[u] = 0;

        if(build(1, mid * 2)){
            l = mid + 1;
            ans = max(ans, mid * 2);
        }else r = mid - 1;
    }
    l = 1; r = n;
    while(l <= r){
        int mid = (l + r) / 2;
        FOR(u, 1, n) del[u] = 0;

        if(build(1, mid * 2 + 1)){
            l = mid + 1;
            ans = max(ans, mid * 2 + 1);
        }else r = mid - 1;
    }
    cout << ans;
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    inp("in.txt");
//    out("out.txt");
    int t = 1;
//    cin >> t;
    while(t--){
        solve();
    }
}

Compilation message (stderr)

lampice.cpp: In function 'int main()':
lampice.cpp:17:47: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 | #define inp(name) if(fopen(name, "r")) freopen(name, "r", stdin);
      |                                        ~~~~~~~^~~~~~~~~~~~~~~~~~
lampice.cpp:133:5: note: in expansion of macro 'inp'
  133 |     inp("in.txt");
      |     ^~~

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