Submission #1001768

#	Time	Username	Problem	Language	Result	Execution time	Memory
1001768		Unforgettablepl	Capital City (JOI20_capital_city)	C++17	11 / 100	622 ms	52228 KiB

capital_city

#include <bits/stdc++.h>
using namespace std;

#define int long long

void strat1(int n){
    int k;
    cin >> k;
    vector<vector<int>> adj(n+1);
    for(int i=1;i<n;i++){
        int a,b;cin>>a>>b;
        adj[a].emplace_back(b);
        adj[b].emplace_back(a);
    }
    vector<int> col(n+1);
    for(int i=1;i<=n;i++)cin>>col[i];
    vector<int> nodes(k+1);
    function<void(int,int,int)> dfs = [&](int x,int par,int dep){
        nodes[col[x]] = x;
        for(int&i:adj[x])if(i!=par)dfs(i,x,dep+1);
    };
    dfs(1,0,1);
    vector<vector<int>> compoadj(k+1);
    for(int i=1;i<=k;i++){
        set<int> bad;
        function<bool(int,int)> pdfs = [&](int x,int p){
            bool found = col[x]==i;
            for(int&i:adj[x])if(i!=p)if(pdfs(i,x))found=true;
            if(found)bad.insert(col[x]);
            return found;
        };
        pdfs(nodes[i],0);
        for(int x:bad)compoadj[i].emplace_back(x);
    }
    vector<bool> visited(k+1);
    int siz = 0;
    function<void(int)> compodfs = [&](int x){
        if(visited[x])return;
        siz++;
        visited[x]=true;
        for(int&i:compoadj[x])compodfs(i);
    };
    int ans = n;
    for(int i=1;i<=k;i++){
        siz = 0;
        visited = vector<bool>(k+1);
        compodfs(i);
        ans = min(ans,siz-1);
    }
    cout << ans << '\n';
}

int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    if(n<=2000){
        strat1(n);
        return 0;
    }
    int k;
    cin >> k;
    vector<vector<int>> adj(n+1);
    for(int i=1;i<n;i++){
        int a,b;cin>>a>>b;
        adj[a].emplace_back(b);
        adj[b].emplace_back(a);
    }
    vector<int> colcor(n+1);
    vector<int> col(n+1);
    for(int i=1;i<=n;i++)cin>>colcor[i];
    function<void(int,int,int)> dfs = [&](int x,int par,int idx){
        col[idx] = colcor[x];
        for(int&i:adj[x])if(i!=par)dfs(i,x,idx+1);
    };
    for(int i=1;i<=n;i++)if(adj[i].size()==1){
        dfs(i,0,1);
        break;
    }
    vector<int> minidx(k+1);
    vector<int> maxidx(k+1);
    for(int i=1;i<=n;i++)maxidx[col[i]]=i;
    for(int i=n;i;i--)minidx[col[i]]=i;
    vector<vector<int>> compoadj(k+1);
    vector<vector<int>> comporevadj(k+1);
    for(int i=1;i<=k;i++){
        for(int x=minidx[i];x<=maxidx[i];x++){
            if(col[x]!=i){
                compoadj[i].emplace_back(col[x]);
                comporevadj[col[x]].emplace_back(i);
                x = maxidx[col[x]];
            }
        }
    }
    vector<bool> visited(k+1);
    vector<int> order;
    vector<int> siz(k+1);
    vector<int> mycompo(k+1);
    function<void(int)> topo = [&](int x){
        if(visited[x])return;
        visited[x]=true;
        for(int&i:compoadj[x])topo(i);
        order.emplace_back(x);
    };
    for(int i=1;i<=k;i++)if(!visited[i])topo(i);
    reverse(order.begin(),order.end());
    function<void(int,int)> cr_dfs = [&](int x,int compo){
        if(mycompo[x]){
            if(mycompo[x]!=compo)siz[mycompo[x]]=n+1;
            return;
        }
        siz[compo]++;
        mycompo[x] = compo;
        for(int&i:comporevadj[x])cr_dfs(i,compo);
    };
    int components = 0;
    int ans = n+1;
    for(int i=0;i<k;i++)if(mycompo[order[i]]==0)cr_dfs(order[i],++components);
    for(int i=1;i<=components;i++){
        ans = min(ans,siz[components]-1);
    }
    cout << ans << '\n';
}

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