Submission #407584

#	Time	Username	Problem	Language	Result	Execution time	Memory
407584		balbit	Mergers (JOI19_mergers)	C++14	100 / 100	1477 ms	160580 KiB

mergers

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define y1 zck_is_king
#define pii pair<int, int>
#define ull unsigned ll
#define f first
#define s second
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define SQ(x) (x)*(x)
#define MN(a,b) a = min(a,(__typeof__(a))(b))
#define MX(a,b) a = max(a,(__typeof__(a))(b))
#define pb push_back
#define REP(i,n) for (int i = 0; i<n; ++i)
#define RREP(i,n) for (int i = n-1; i>=0; --i)
#define REP1(i,n) for (int i = 1; i<=n; ++i)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#ifdef BALBIT
#define IOS()
#define bug(...) fprintf(stderr,"#%d (%s) = ",__LINE__,#__VA_ARGS__),_do(__VA_ARGS__);
template<typename T> void _do(T &&x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T &&x, S &&...y){cerr<<x<<", ";_do(y...);}
#else
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'
#define bug(...)
#endif

const int iinf = 1e9+10;
const ll inf = 1ll<<60;
const ll mod = 1e9+7 ;


void GG(){cout<<"0\n"; exit(0);}

ll mpow(ll a, ll n, ll mo = mod){ // a^n % mod
    ll re=1;
    while (n>0){
        if (n&1) re = re*a %mo;
        a = a*a %mo;
        n>>=1;
    }
    return re;
}

ll inv (ll b, ll mo = mod){
    if (b==1) return b;
    return (mo-mo/b) * inv(mo%b,mo) % mo;
}

const int maxn = 5e5+5;

vector<int> g[maxn];
int dpar[maxn];
int par[maxn], dep[maxn];

void dfs(int v, int p) {
    par[v] = p;
    for (int u : g[v]) {
        if (u != p) {
            dep[u] = dep[v] + 1;
            dfs(u,v);
        }
    }
}

vector<int> where[maxn];
int find (int x ) {return x == dpar[x] ? x : dpar[x] = find(dpar[x]); }
void mrg(int a,int b ) {
    a = find(a); b = find(b);
    if (dep[a] > dep[b]) swap(a,b); // a is new root;
    dpar[b] = a;
}

set<int> adj[maxn];

signed main(){
    IOS();
    int n,k; cin>>n>>k;
    vector<pii> E;
    REP(i,n-1) {
        int a,b; cin>>a>>b; --a; --b;
        E.pb({a,b});
        g[a].pb(b); g[b].pb(a);
    }
    dfs(0, -1);
    REP(i,n) dpar[i ]= i;
    REP(i,n) {
        int x; cin>>x;
        where[x-1].pb(i);
    }
    REP(c, k) {
        int tmp = where[c][0];
        tmp = find(tmp);
        for (int i = 1; i<SZ(where[c]); ++i) {
            int v = where[c][i];
            v = find(v);
            while (v != tmp) {
                if (dep[v] < dep[tmp]) swap(v, tmp);
                // move v
                mrg(v, par[v]);
                v = find(v);
                bug(v, tmp);
            }
        }
    }
    for (pii p : E) {
        if(find (p.f) != find(p.s)) {
            adj[find(p.f)].insert(find(p.s));
            adj[find(p.s)].insert(find(p.f));
        }
    }
    int lf = 0;
    REP(i,n) {
        if (find (i) == i) {
            if (SZ(adj[i]) == 1) lf++;
        }
    }
    assert(lf != 1);
    cout<<(lf+1)/2<<endl;
}

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