Submission #417599

#	Time	Username	Problem	Language	Result	Execution time	Memory
417599		cpp219	Mergers (JOI19_mergers)	C++14	100 / 100	1912 ms	106832 KiB

mergers

#pragma GCC optimization "O2"
#pragma GCC optimization "unroll-loop"
#pragma GCC target ("avx2")

#include <bits/stdc++.h>
#define ll int
#define ld long double
#define fs first
#define sc second
using namespace std;
const ll N = 5e5 + 9;
const ll inf = 1e9 + 7;
typedef pair<ll,ll> LL;
vector<ll> g[N],c[N];
ll n,k,x,y,in[N],out[N],nTime = 1,grp[N],cnt[N];
ll par[N];
void DFS(ll u,ll p){
    in[u] = out[u] = nTime; nTime++;
    par[u] = p;
    for (auto i : g[u])
        if (i != p) DFS(i,u),out[u] = max(out[u],out[i]);
}

ll st[2][4*N]; /// 0 for min   1 for max
void upd(ll cond,ll id,ll l,ll r,ll u,ll val){
    if (u < l||r < u) return;
    if (l == r){
        st[cond][id] = val; return;
    }
    ll mid = (l + r)/2;
    upd(cond,id*2,l,mid,u,val); upd(cond,id*2 + 1,mid + 1,r,u,val);
    if (!cond) st[cond][id] = min(st[cond][id*2],st[cond][id*2 + 1]);
    else st[cond][id] = max(st[cond][id*2],st[cond][id*2 + 1]);
}

ll Get(ll cond,ll id,ll l,ll r,ll u,ll v){
    if (v < l||r < u){
        if (!cond) return inf;
        return 0;
    }
    if (u <= l&&r <= v) return st[cond][id];
    ll mid = (l + r)/2;
    if (!cond) return min(Get(cond,id*2,l,mid,u,v),Get(cond,id*2 + 1,mid + 1,r,u,v));
    return  max(Get(cond,id*2,l,mid,u,v),Get(cond,id*2 + 1,mid + 1,r,u,v));
}
LL edge[N];
ll lab[N];
ll Find(ll u){
    if (lab[u] < 0) return u;
    return lab[u] = Find(lab[u]);
}

void Union(ll p,ll q){
    ll s = Find(p),r = Find(q);
    if (r == s) return;
    if (lab[r] > lab[s]) swap(r,s);
    lab[r] += lab[s]; lab[s] = r;
}

bool Is_Good(ll u){
    ll x = Get(0,1,1,n,in[u],out[u]),y = Get(1,1,1,n,in[u],out[u]);
    if (x < in[u]||y > out[u]) return 1;
    return 0;
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    #define task "tst"
    if (fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        //freopen(task".out", "w", stdout);
    }
    cin>>n>>k;
    for (ll i = 1;i < n;i++){
        cin>>x>>y; edge[i] = {x,y};
        g[x].push_back(y); g[y].push_back(x);
    }
    for (ll i = 1;i <= n;i++) cin>>grp[i],c[grp[i]].push_back(i);
    if (n == 2) return cout<<k - 1,0;
    DFS(1,0); memset(lab,-1,sizeof(lab));
    for (ll i = 1;i <= k;i++){
        ll mn = inf,mx = 0;
        for (auto j : c[i]) mn = min(mn,in[j]),mx = max(mx,out[j]);
        for (auto j : c[i]) upd(0,1,1,n,in[j],mn),upd(1,1,1,n,in[j],mx);
    }
    for (ll i = 2;i <= n;i++){
        if (Is_Good(i)) Union(i,par[i]);
        //cout<<i<<" "<<Is_Good(i)<<"\n";
    }
    for (ll i = 1;i < n;i++){
        ll x = edge[i].fs,y = edge[i].sc;
        if (Find(x) != Find(y)) cnt[Find(x)]++,cnt[Find(y)]++;
    }
    ll leaf = 0;
    for (ll i = 1;i <= n;i++) leaf += (cnt[i] == 1);
    cout<<(leaf + 1)/2;
}

Compilation message (stderr)

mergers.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization "O2"
      | 
mergers.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
mergers.cpp: In function 'int main()':
mergers.cpp:71:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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