Submission #943811

#	Time	Username	Problem	Language	Result	Execution time	Memory
943811		guagua0407	Capital City (JOI20_capital_city)	C++17	100 / 100	2835 ms	472516 KiB

capital_city

#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

const int mxn=2e5+5;
const int inf=1e9;
const int B=17;
vector<int> adj[mxn];
vector<int> adj2[mxn*B],adjr[mxn*B];
bool visited[mxn*B];
int c[mxn];
int up[mxn][B];
int id[mxn][B];
int depth[mxn];
vector<int> belong[mxn];
vector<int> ord;
int L[mxn];
int sz[mxn*B];
int scc[mxn*B];
int out[mxn*B];
int n,k;

void dfs(int v,int p=0){
    up[v][0]=p;
    depth[v]=depth[p]+1;
    for(auto u:adj[v]){
        if(u==p) continue;
        dfs(u,v);
    }
}

void dfs2(int v){
    visited[v]=true;
    for(auto u:adj2[v]){
        if(visited[u]) continue;
        dfs2(u);
    }
    ord.push_back(v);
}

void dfs3(int v,int cur){
    visited[v]=true;
    scc[v]=cur;
    if(v<=k) sz[cur]++;
    for(auto u:adjr[v]){
        if(visited[u]) continue;
        dfs3(u,cur);
    }
}

int lca(int a,int b){
    if(depth[a]<depth[b]) swap(a,b);
    int len=depth[a]-depth[b];
    for(int i=0;i<B;i++){
        if(len&(1<<i)) a=up[a][i];
    }
    if(a==b) return a;
    for(int i=B-1;i>=0;i--){
        int ta=up[a][i];
        int tb=up[b][i];
        if(ta!=tb){
            a=ta;
            b=tb;
        }
    }
    return up[a][0];
}

int main() {_
    cin>>n>>k;
    for(int i=0;i<n-1;i++){
        int a,b;
        cin>>a>>b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    for(int i=1;i<=n;i++){
        cin>>c[i];
        belong[c[i]].push_back(i);
    }
    dfs(1);
    for(int j=1;j<B;j++){
        for(int i=1;i<=n;i++){
            up[i][j]=up[up[i][j-1]][j-1];
        }
    }
    for(int i=1;i<=k;i++){
        L[i]=belong[i][0];
        for(int j=1;j<(int)belong[i].size();j++){
            L[i]=lca(L[i],belong[i][j]);
        }
    }
    int cnt=k;
    for(int i=1;i<=n;i++){
        id[i][0]=c[i];
    }
    for(int j=1;j<B;j++){
        for(int i=1;i<=n;i++){
            id[i][j]=++cnt;
            adj2[id[i][j]].push_back(id[i][j-1]);
            adj2[id[i][j]].push_back(id[up[i][j-1]][j-1]);
        }
    }
    for(int i=1;i<=k;i++){
        //cout<<L[i]<<'\n';
        for(auto v:belong[i]){
            int bit=__lg(depth[v]-depth[L[i]]+1);
            adj2[i].push_back(id[v][bit]);
            int len=depth[v]-(depth[L[i]]+(1<<bit)-1);
            int x=v;
            for(int j=0;j<B;j++){
                if(len&(1<<j)) x=up[x][j];
            }
            adj2[i].push_back(id[x][bit]);
            //cout<<v<<' '<<x<<' '<<bit<<'\n';

        }
    }
    for(int i=1;i<=cnt;i++){
        for(auto u:adj2[i]){
            adjr[u].push_back(i);
        }
    }
    fill(visited+1,visited+cnt+1,false);
    for(int i=1;i<=cnt;i++){
        if(!visited[i]){
            dfs2(i);
        }
    }
    reverse(all(ord));
    fill(visited+1,visited+cnt+1,false);
    int sccnt=0;
    for(auto i:ord){
        if(!visited[i]){
            ++sccnt;
            dfs3(i,sccnt);
        }
    }
    for(int i=1;i<=cnt;i++){
        for(auto u:adj2[i]){
            if(scc[u]!=scc[i]) out[scc[i]]++;
        }
    }
    int ans=inf;
    for(int i=1;i<=sccnt;i++){
        if(out[i]==0 and sz[i]>0) ans=min(ans,sz[i]-1);
    }
    cout<<ans<<'\n';
    return 0;
}
//maybe its multiset not set
//yeeorz
//laborz

Compilation message (stderr)

capital_city.cpp: In function 'void setIO(std::string)':
capital_city.cpp:15:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
capital_city.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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