Submission #960897

#	Time	Username	Problem	Language	Result	Execution time	Memory
960897		GrindMachine	Mergers (JOI19_mergers)	C++17	100 / 100	1588 ms	166728 KiB

mergers

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*

refs:
hints from edi

*/

const int MOD = 1e9 + 7;
const int N = 5e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<int> adj1[N], adj2[N];
    
struct lca_algo {
    // LCA template (for graphs with 1-based indexing)
 
    int LOG = 1;
    vector<int> depth;
    vector<vector<int>> up;
    vector<int> tin, tout;
    int timer = 1;
 
    lca_algo() {
 
    }
 
    lca_algo(int n) {
        lca_init(n);
    }
 
    void lca_init(int n) {
        while ((1 << LOG) < n) LOG++;
        up = vector<vector<int>>(n + 1, vector<int>(LOG, 1));
        depth = vector<int>(n + 1);
        tin = vector<int>(n + 1);
        tout = vector<int>(n + 1);
 
        lca_dfs(1, -1);
    }
 
    void lca_dfs(int node, int par) {
        tin[node] = timer++;
 
        trav(child, adj1[node]) {
            if (child == par) conts;
 
            up[child][0] = node;
            rep1(j, LOG - 1) {
                up[child][j] = up[up[child][j - 1]][j - 1];
            }
 
            depth[child] = depth[node] + 1;
 
            lca_dfs(child, node);
        }
 
        tout[node] = timer-1;
    }
 
    int lift(int u, int k) {
        rep(j, LOG) {
            if (k & (1 << j)) {
                u = up[u][j];
            }
        }
 
        return u;
    }

    int query(int u, int v) {
        if (depth[u] < depth[v]) swap(u, v);
        int k = depth[u] - depth[v];
        u = lift(u, k);
 
        if (u == v) return u;
 
        rev(j, LOG - 1, 0) {
            if (up[u][j] != up[v][j]) {
                u = up[u][j];
                v = up[v][j];
            }
        }
 
        u = up[u][0];
        return u;
    }
 
    int get_dis(int u, int v) {
        int lca = query(u, v);
        return depth[u] + depth[v] - 2 * depth[lca];
    }
 
    bool is_ances(int u, int v){
        return tin[u] <= tin[v] and tout[u] >= tout[v];
    }
};

vector<int> here[N];
vector<int> a(N);
vector<int> bad_cnt(N);

void dfs1(int u, int p){
    trav(v,adj1[u]){
        if(v == p) conts;
        dfs1(v,u);
        bad_cnt[u] += bad_cnt[v];
    }
}

vector<int> col(N);
vector<bool> vis(N);

void dfs2(int u, int p, int c){
    vis[u] = 1;
    col[u] = c;
    trav(v,adj2[u]){
        if(v == p) conts;
        dfs2(v,u,c);
    }
}

void solve(int test_case)
{
    int n,k; cin >> n >> k;
    rep1(i,n-1){
        int u,v; cin >> u >> v;
        adj1[u].pb(v), adj1[v].pb(u);
    }
    rep1(i,n) cin >> a[i];

    rep1(i,n) here[a[i]].pb(i);
    lca_algo LCA(n);

    rep1(c,k){
        auto &nodes = here[c];
        int lca = nodes[0];
        trav(u,nodes){
            lca = LCA.query(lca,u);
        }

        trav(u,nodes){
            bad_cnt[u]++;
            bad_cnt[lca]--;
        }
    }

    dfs1(1,-1);

    rep1(u,n){
        trav(v,adj1[u]){
            if(LCA.depth[v] > LCA.depth[u]){
                if(bad_cnt[v]){
                    adj2[u].pb(v), adj2[v].pb(u);
                }
            }
        }
    }

    int ptr = 0;
    rep1(u,n){
        if(vis[u]) conts;
        dfs2(u,-1,++ptr);
    }

    vector<int> deg(n+5);

    rep1(u,n){
        trav(v,adj1[u]){
            if(u < v and col[u] != col[v]){
                deg[col[u]]++, deg[col[v]]++;
            }
        }
    }

    int ans = 0;

    if(ptr > 1){
        int leaves = 0;
        rep1(c,ptr) leaves += (deg[c] == 1);
        ans = ceil2(leaves,2);
    }

    cout << ans << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

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