Submission #941996

#	Time	Username	Problem	Language	Result	Execution time	Memory
941996		guagua0407	Capital City (JOI20_capital_city)	C++17	0 / 100	20 ms	32860 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=2000+5;
const int inf=1e9;
vector<int> adj[mxn],adj2[mxn],adjr[mxn];
bool visited[mxn];
int c[mxn];
vector<vector<int>> belong(mxn);
int n,k;
vector<vector<int>> mp(mxn,vector<int>(mxn));
vector<bool> did(mxn);
vector<int> ord;
int cnt[mxn];
int scc[mxn];
int in[mxn];
int top[mxn];
bool no[mxn];
int up[mxn][20];
int depth[mxn];

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<20;i++){
        if(len&(1<<i)) a=up[a][i];
    }
    if(a==b) return a;
    for(int i=19;i>=0;i--){
        int ta=up[a][i];
        int tb=up[b][i];
        if(ta!=tb){
            a=ta;
            b=tb;
        }
    }
    return up[a][0];
}

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

void dfsr(int v,int id){
    visited[v]=true;
    scc[v]=id;
    cnt[id]++;
    for(auto u:adjr[v]){
        if(visited[u]) continue;
        dfsr(u,id);
    }
}

void dfs1(int v,int p=0){
    depth[v]=depth[p]+1;
    up[v][0]=p;
    for(auto u:adj[v]){
        if(u==p) continue;
        dfs1(u,v);
    }
}

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];
        c[i]--;
        belong[c[i]].push_back(i);
    }
    dfs1(1);
    for(int j=1;j<20;j++){
        for(int i=1;i<=n;i++){
            up[i][j]=up[up[i][j-1]][j-1];
        }
    }
    for(int i=0;i<k;i++){
        for(int j=0;j<k;j++){
            did[j]=false;
        }
        for(int j=1;j<=n;j++){
            visited[j]=false;
        }
        int node=belong[i][0];
        for(int j=1;j<belong[i].size();j++){
            node=lca(node,belong[i][j]);
        }
        vector<int> vec;
        for(auto v:belong[i]){
            while(!visited[v] and v!=up[node][0]){
                vec.push_back(v);
                visited[v]=true;
                v=up[v][0];
            }
        }
        for(auto v:vec){
            int x=c[v];
            if(x!=i and !did[x]){
                did[x]=true;
                for(auto u:belong[x]){
                    if(!visited[u]){
                        adj2[i].push_back(x);
                        adjr[x].push_back(i);
                        break;
                    }
                }
            }
        }
    }
    fill(visited,visited+mxn,false);
    for(int i=0;i<k;i++){
        if(!visited[i]){
            dfs(i);
        }
    }
    reverse(all(ord));
    fill(visited,visited+mxn,false);
    int sccnt=0;
    for(int i=0;i<k;i++){
        if(!visited[ord[i]]){
            dfsr(ord[i],sccnt);
            sccnt++;
        }
    }
    for(int i=0;i<k;i++){
        for(auto u:adj2[i]){
            //cout<<i+1<<' '<<u+1<<'\n';
            if(scc[i]==scc[u]) continue;
            in[scc[i]]++;
        }
    }
    int ans=inf;
    for(int i=0;i<sccnt;i++){
        if(in[i]==0) ans=min(ans,cnt[i]-1);
    }
    cout<<ans<<'\n';
    return 0;
}
//maybe its multiset not set
//yeeorz
//laborz

Compilation message (stderr)

capital_city.cpp: In function 'int main()':
capital_city.cpp:110:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  110 |         for(int j=1;j<belong[i].size();j++){
      |                     ~^~~~~~~~~~~~~~~~~
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: 0 / 1
• Subtask 2: 0 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 59