Submission #676766

#	Time	Username	Problem	Language	Result	Execution time	Memory
676766		victor_gao	Capital City (JOI20_capital_city)	C++17	11 / 100	913 ms	524288 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,cap[N],dep[N],fa[N];
vector<int>g[N],col[N],G[N];
vector<pii>edge;
int dfn[N],low[N],dft=0,boss[N],val[N],dp[N],nscc=0,deg[N];
bool ins[N],vis[N];
stack<int>st;
void dfs(int p,int lp){
    fa[p]=lp;
    dep[p]=dep[lp]+1;
    for (auto i:g[p])
        if (i!=lp)
            dfs(i,p);
}
int jump(int a,int b,int c){
    while (a!=b){
      //  cout<<a<<" "<<b<<' '<<c<<'\n';
        if (dep[a]<dep[b]) swap(a,b);
        G[c].push_back(cap[a]);
       // cout<<"add "<<c<<" "<<cap[a]<<'\n';
        edge.push_back({c,cap[a]});
        a=fa[a];
    }
    G[c].push_back(cap[a]);
    edge.push_back({c,cap[a]});
    return a;
}
void tarjan(int p){
    dfn[p]=low[p]=++dft;
    st.push(p); ins[p]=1;
    for (auto i:G[p]){
        if (!dfn[i]){
            tarjan(i);
            low[p]=min(low[p],low[i]);
        }
        else if (ins[i]&&dfn[i]<dfn[p])
            low[p]=min(low[p],dfn[i]);
    }
    if (low[p]==dfn[p]){
        nscc++;
        for (int x=0;x!=p;st.pop()){
            x=st.top(); ins[x]=0;
            boss[x]=nscc;
            val[nscc]++;
        }
    }
}
void build(){
    for (int i=0;i<n;i++)
        G[i].clear();
    for (auto i:edge){
        if (boss[i.x]!=boss[i.y]){
            deg[boss[i.x]]++;
        }
    }
}
signed main(){
   // fast
    cin>>n>>k;
    for (int i=1;i<n;i++){
        int a,b; cin>>a>>b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    for (int i=1;i<=n;i++){
        cin>>cap[i];
        col[cap[i]].push_back(i);
    }
    dfs(1,0);
    for (int i=1;i<=k;i++){
        while (col[i].size()>1){
            int a=col[i].back(); col[i].pop_back();
            int b=col[i].back(); col[i].pop_back();
            col[i].push_back(jump(a,b,i));
        }
    }
    int ans=1e9;
    for (int i=1;i<=k;i++)
        if (!dfn[i])
            tarjan(i);
    build();
    for (int i=1;i<=k;i++)
        if (deg[boss[i]]==0)
            ans=min(ans,val[boss[i]]);
    cout<<ans-1<<'\n';
}

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