Submission #1014840

#	Time	Username	Problem	Language	Result	Execution time	Memory
1014840		underwaterkillerwhale	Cat Exercise (JOI23_ho_t4)	C++17	100 / 100	183 ms	49272 KiB

Main

//#include "pour.h"
#include <bits/stdc++.h>
#define se              second
#define fs              first
#define mp              make_pair
#define pb              push_back
#define ll              long long
#define ii              pair<ll,ll>
#define ld              long double
#define SZ(v)           (int)v.size()
#define ALL(v)          v.begin(), v.end()
#define bit(msk, i)     ((msk >> i) & 1)
#define iter(id, v)     for(auto id : v)
#define rep(i,m,n)      for(int i=(m); i<=(n); i++)
#define reb(i,m,n)      for(int i=(m); i>=(n); i--)

using namespace std;

mt19937_64 rd(chrono :: steady_clock :: now().time_since_epoch().count());
ll Rand(ll l, ll r)
{
    return uniform_int_distribution<ll> (l, r)(rd);
}

const int N  = 2e5 + 7;
const int Mod = 111539786;
const int szBL = 916;
const ll INF = 1e18;
const int BASE = 137;

int n, m;
vector<int> ke[N];
int a[N];
ll dp[N];
int high[N], par[N][25];

void dfs (int u, int p) {
    high[u] = high[p] + 1;
    par[u][0] = p;
    rep (i, 1, 20) par[u][i] = par[par[u][i - 1]][i - 1];
    iter (&v, ke[u]) if (v != p) {
        dfs (v, u);
    }
}

int Lca (int u, int v) {
    if (high[v] < high[u]) swap (u, v);
    int delta = high[v] - high[u];
    rep (i, 0, 20) if (bit(delta, i)) {
        v = par[v][i];
    }
    if (v == u) return v;
    reb (i, 20, 0) {
        if (par[u][i] != par[v][i]) {
            u = par[u][i];
            v = par[v][i];
        }
    }
    return par[v][0];
}

int Dist (int u, int v) {
    return high[u] + high[v] - 2 * high[Lca(u, v)];
}


struct Disjoin_set {
    int lab[N], sz[N], mx[N];

    void init (int n) {
        rep (i, 1, n) lab[i] = i, sz[i] = 1, mx[i] = i;
    }
    int Find (int u) {
        return u == lab[u] ? u : lab[u] = Find(lab[u]);
    }
    void Join (int u, int v) {
        u = Find(u);
        v = Find(v);
        if (u == v) return;
        if (sz[u] < sz[v]) swap (u, v);
        sz[u] += sz[v];
        lab[v] = u;
        mx[u] = max(mx[u], mx[v]);
    }
}DSU;

void solution () {
    cin >> n;
    rep (i, 1, n) {
        cin >> a[i];
    }
    rep (i, 1, n - 1) {
        int u, v;
        cin >> u >> v;
        ke[a[u]].push_back(a[v]);
        ke[a[v]].push_back(a[u]);
    }
    dfs (1, 0);
    DSU.init (n);
    dp[1] = 0;
    rep (u, 1, n) {
        iter (&v, ke[u]) {
            if (u > v) {
                int mx = DSU.mx[DSU.Find(v)];
                dp[u] = max(dp[u], dp[mx] + Dist(u, mx));
                DSU.Join(u, v);
            }
        }
//        cout << dp[u] <<"\n";
    }
    cout << dp[n] <<"\n";
}

#define file(name) freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout);
int main () {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
//    file ("c");
    int num_Test = 1;
//    cin >> num_Test;
    while (num_Test--)
        solution();
}
/*
3 2
0 1 1
0 0 1
0 0 0
3 3
1 2
*/

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