Submission #676752

#	Time	Username	Problem	Language	Result	Execution time	Memory
676752		victor_gao	Capital City (JOI20_capital_city)	C++17	0 / 100	249 ms	31428 KiB

capital_city

//#pragma GCC optimize("Ofast,unroll-loops,O3")
//#pragma GCC optimize("avx,avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,fma,tune=native")
#include<bits/stdc++.h>
//#include<bits/extc++.h>
//#pragma pack(1)
#define fast ios::sync_with_stdio(0); cin.tie(0);
#define int long long
#define pii pair<int,int>
#define x first
#define y second
#define N 200015
using namespace std;
//using namespace __gnu_pbds;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//typedef tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update> order_multiset;
//typedef tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> order_set;
int n,k,deg[N],cap[N],cnt[N],vis[N],tans=0,now=0;
vector<pii>edge;
vector<pii>g[N];
map<pii,int>mp;
set<int>st;
void dfs(int p){
    vis[p]=1; now+=cnt[p]; tans++;
    st.insert(p);
    for (auto i:g[p]){
        if (!vis[i.x]){
            dfs(i.x);
        }
    }
}
signed main(){
    fast
    cin>>n>>k;
    for (int i=1;i<n;i++){
        int a,b; cin>>a>>b;
        edge.push_back({a,b});
    }
    for (int i=1;i<=n;i++){
        cin>>cap[i];
        cnt[cap[i]]++;
    }
    for (auto i:edge){
        if (cap[i.x]==cap[i.y]){
            cnt[cap[i.x]]--;
            continue;
        }
        int a=cap[i.x],b=cap[i.y];
        if (a>b) swap(a,b);
        mp[{a,b}]++;
    }
    for (auto i:mp){
        int a=i.x.x,b=i.x.y;
        if (i.y>1){
            g[a].push_back({b,i.y});
            g[b].push_back({a,i.y});
        }
        deg[a]+=i.y; deg[b]+=i.y;
    }
    int ans=k;
    for (int i=1;i<=k;i++){
        if (cnt[i]==1)
            ans=1;
    }
    queue<int>q;
    for (int i=1;i<=k;i++){
        if (deg[i]==cnt[i]){
            q.push(i);
        }
    }
    while (!q.empty()){
        int p=q.front(); q.pop();
        vis[p]=1;
        for (auto i:g[p]){
            deg[i.x]-=i.y;
            if (deg[i.x]==cap[i.x])
                q.push(i.x);
        }
    }
    for (int i=1;i<=k;i++){
        if (!vis[i]){
            st.clear();
            now=0; tans=0;
            dfs(i);
            int total=0;
            for (auto j:st){
                for (auto l:g[j]){
                    if (st.find(l.x)!=st.end())
                        total+=l.y;
                }
            }
            total/=2;
            if (total==now-1)
                ans=min(tans,ans);
        }
    }
    cout<<ans-1<<'\n';
}

• Subtask 1: 0 / 1
• Subtask 2: 0 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 59