Submission #1250737

#	Time	Username	Problem	Language	Result	Execution time	Memory
1250737		CrabCNH	Cat Exercise (JOI23_ho_t4)	C++20	31 / 100	170 ms	14404 KiB

Main

#include <bits/stdc++.h>

#define task     "BriantheCrab"

#define int    long long
#define pii    pair <int, int>
#define fi     first
#define se     second
#define szf    sizeof
#define sz(s)  (int)((s).size())
#define all(v) (v).begin(), (v).end()

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

using namespace std;

template <class T> void minimize (T &t, T f) {if (t > f) t = f;}
template <class T> void maximize (T &t, T f) {if (t < f) t = f;}

const int maxN = 2e5 + 5;
const int inf = 1e18 + 7;
const int mod = 1e9 + 7;

// khong tu code thi khong kha len duoc dau

int n;
int p[maxN];
vector <int> adj[maxN];

namespace sub4 {
    const int maxN = 5e3 + 5;
    
    int dp[maxN];
    int mark[maxN];
    
    struct cc {
        int node, val, dis; 
    };
    
    cc find (int u, int par, int d) {
        cc best = {u, p[u], d};
        for (auto v : adj[u]) {
            if (v == par || mark[v]) {
                continue;
            }
            cc nxt = find (v, u, d + 1);
            if (nxt.val > best.val) {
                best = nxt;
            }
        }
        //cout << best.node << '\n';
        return best;
    }
    
    void dfs (int u, int par) {
        mark[u] = 1;
        for (auto v : adj[u]) {
            if (v == par || mark[v]) {
                continue;
            }
            cc nxt = find (v, u, 1);
            dfs (nxt.node, nxt.node);
            //cout << nxt.node << ' ' << nxt.dis << '\n';
            maximize (dp[u], dp[nxt.node] + nxt.dis);
            
        }
    }
    
    void sol () {
        for (int i = 1; i <= n; i ++) {
            if (p[i] == n) {
                dfs (i, i);
                cout << dp[i];
                return;
            }
        }
    }
}

void solve () {
    cin >> n;
    for (int i = 1; i <= n; i ++) {
        cin >> p[i];
    }    
    for (int i = 1; i <= n - 1; i ++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back (v);
        adj[v].push_back (u);
    }
    if (n <= 5e3) {
        sub4 :: sol ();
    }
    return;
}

signed main () {
    cin.tie (nullptr) -> sync_with_stdio (false);
    if (fopen (task".inp", "r")) {
        freopen (task".inp", "r", stdin);
        freopen (task".out", "w", stdout);
    }
    int t = 1;
    //cin >> t;
    while (t --) {
        solve ();
    } 
    return 0;
}
// thfv

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:102:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:103:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  103 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 10 / 10
• Subtask 5: 0 / 20
• Subtask 6: 0 / 23
• Subtask 7: 0 / 26