Submission #944300

#	Time	Username	Problem	Language	Result	Execution time	Memory
944300		VinhLuu	Mergers (JOI19_mergers)	C++17	0 / 100	41 ms	56012 KiB

mergers

//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

#include <bits/stdc++.h>
//#define int long long
#define ll long long
#define fi first
#define se second
#define pb push_back
#define all(lmao) lmao.begin(), lmao.end()

using namespace std;

typedef pair<int,int> pii;
typedef tuple<int,int,int> tp;
const int N = 5e5 + 5;
const ll oo = 1e16;
const int mod = 1e9 + 7;
const int base = 23;

int n, k, X[N], Y[N], col[N], a[N], f[N], dp[N], in[N], en[N], demin, b[N];
vector<int> p[N], g[N], vr[N], m;
bool fl[N];

void pre(int u,int v){
    f[u] = a[u];
    dp[u] = 1;
    in[u] = ++demin;
    b[demin] = u;
    for(auto j : p[u]){
        if(j == v) continue;
        pre(j, u);
        f[u] += f[j];
        dp[u] += dp[j];
    }
    en[u] = demin;
}

void dfs(int u,int v){
    if(dp[u] == f[u]){
        m.pb(u);
        return;
    }
    for(auto j : p[u]){
        if(j == v) continue;
        dfs(j, u);
    }
}

signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    #define task "v"
    if(fopen(task ".inp","r")){
        freopen(task ".inp","r",stdin);
        freopen(task ".out","w",stdout);
    }

    cin >> n >> k;

    for(int i = 1; i <= n - 1; i ++){
        cin >> X[i] >> Y[i];
        p[X[i]].pb(Y[i]);
        p[Y[i]].pb(X[i]);
    }
    int root = 1;
    for(int i = 1; i <= n; i ++){
        if((int)p[i].size() >= 2) root = i;
        int x; cin >> x;
        vr[x].pb(i);
        col[i] = x;
    }
    for(int i = 1; i < n; i ++){
        if(col[X[i]] == col[Y[i]]){
            g[X[i]].pb(Y[i]);
            g[Y[i]].pb(X[i]);
        }
    }
    if(n == 2){
        if(col[1] == col[2]){
            cout << 0 << "\n";
        }else cout << 1 << "\n";
        return 0;
    }

    for(int i = 1; i <= k; i ++){
        queue<int> q;
        q.push(vr[i][0]);
        fl[vr[i][0]] = true;
        while(!q.empty()){
            int u = q.front();
            q.pop();
            for(auto j : g[u]){
                if(fl[j]) continue;
                fl[j] = true;
                q.push(j);
            }
        }
        bool ff = true;
        for(auto j : vr[i]){
            if(!fl[j]){
                ff = false;
                break;
            }
        }
        if(ff) for(auto j : vr[i]) a[j] = 1;
    }
    pre(root, 0);
    dfs(root, 0);
    int ans = 0;
    for(auto j : m){
        set<int> st;
        for(int i = in[j]; i <= en[j]; i ++) st.insert(col[b[i]]);
        ans += ((int)st.size() - 1);
    }
    ans += max(0, (int)m.size() - 1);
    cout << ans;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:55:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   55 |         freopen(task ".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
mergers.cpp:56:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   56 |         freopen(task ".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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