Submission #694208

#	Time	Username	Problem	Language	Result	Execution time	Memory
694208		Do_you_copy	Mergers (JOI19_mergers)	C++17	70 / 100	140 ms	32800 KiB

mergers

//Then
#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
#define faster ios_base::sync_with_stdio(0); cin.tie(0);

using namespace std;
using ll = long long;
using ld = long double;
using pii = pair <int, int>;
mt19937_64 Rand(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e5 + 1;
//const int Mod = 1e9 + 7;
//const int inf =
int n, k;
int id[maxN];
int lab[maxN];
vector <int> S[maxN];
int sum[maxN];
pii e[maxN];
vector <int> adj[maxN], adj1[maxN];
int depth[maxN], lift[maxN][20];
int find_set(int u){
    return lab[u] < 0 ? u : lab[u] = find_set(lab[u]);
}

bool unite(int u, int v){
    u = find_set(u);
    v = find_set(v);
    if (u == v) return 0;
    lab[u] += lab[v];
    lab[v] = u;
    return 1;
}

inline int lca(int u, int v){
    if (depth[u] < depth[v]) swap(u, v);
    int k = depth[u] - depth[v];
    while (k){
        int t = __lg(k);
        u = lift[u][t];
        k ^= 1 << t;
    }
    if (u == v) return u;
    for (int i = 19; i >= 0; --i){
        if (lift[u][i] == lift[v][i]) continue;
        u = lift[u][i];
        v = lift[v][i];
    }
    return lift[u][0];
}

void dfs(int u, int p){
    depth[u] = depth[p] + 1;
    lift[u][0] = p;
    for (int i = 1; i < 20; ++i) lift[u][i] = lift[lift[u][i - 1]][i - 1];
    for (int i: adj[u]){
        if (i == p) continue;
        dfs(i, u);
    }
}

void dfs1(int u, int p){
    for (int i: adj[u]){
        if (i == p) continue;
        dfs1(i, u);
        sum[u] += sum[i];
    }
    if (sum[u] < 0){
        unite(id[u], id[p]);
    }
}

int leaf;
void dfs2(int u, int p){
    if (adj1[u].size() == 1) ++leaf;
    for (int i: adj1[u]){
        if (i == p) continue;
        dfs2(i, u);
    }
}

void Init(){
    cin >> n >> k;
    for (int i = 1; i < n; ++i){
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
        e[i] = {u, v};
    }
    for (int i = 1; i <= n; ++i){
        cin >> id[i];
        S[id[i]].pb(i);
    }
    fill(lab + 1, lab + n + 1, -1);
    dfs(1, 0);
    for (int i = 1; i <= k; ++i){
        int root = S[i][0];
        for (int j = 1; j < signed(S[i].size()); ++j){
            root = lca(root, S[i][j]);
        }
        for (int j: S[i]){
            --sum[j];
        }
        sum[root] += S[i].size();
    }
    dfs1(1, 0);
    for (int i = 1; i < n; ++i){
        int u = find_set(id[e[i].fi]);
        int v = find_set(id[e[i].se]);
        if (u == v) continue;
        adj1[u].pb(v);
        adj1[v].pb(u);
    }
    for (int i = 1; i <= k; ++i){
        if (adj1[i].size()){
            dfs2(i, 0);
            break;
        }
    }
    cout << (leaf + 1) / 2;
}

#define debug
#define taskname "test"
signed main(){
    faster
    if (fopen(taskname".inp", "r")){
        freopen(taskname".inp", "r", stdin);
        freopen(taskname".out", "w", stdout);
    }
    int tt = 1;
    //cin >> tt;
    while (tt--){
        Init();
    }
    if (fopen("timeout.txt", "r")){
        ofstream timeout("timeout.txt");
        timeout << signed(double(clock()) / CLOCKS_PER_SEC * 1000);
        timeout.close();
        #ifndef debug
        cerr << "Time elapsed: " << signed(double(clock()) / CLOCKS_PER_SEC * 1000) << "ms\n";
        #endif // debug
    }
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:131:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  131 |         freopen(taskname".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
mergers.cpp:132:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  132 |         freopen(taskname".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 0 / 30