Submission #637868

#	Time	Username	Problem	Language	Result	Execution time	Memory
637868		Cross_Ratio	Capital City (JOI20_capital_city)	C++14	0 / 100	862 ms	37656 KiB

capital_city

#include <bits/stdc++.h>
using namespace std;
vector<vector<int>> adj;
int C[200005];
bool vis[200005];
int sz[200005];
vector<vector<int>> B;
int get_sz(int c, int p) {
    sz[c] = 1;
    for(int n : adj[c]) {
        if(n==p || vis[n]) continue;
        sz[c] += get_sz(n, c);
    }
    return sz[c];
}
int get_cent(int c, int p, int s) {
    for(int n : adj[c]) {
        if(n==p || vis[n]) continue;
        if(sz[n] > s/2) return get_cent(n, c, s);
    }
    return c;
}
int N, K;
int par[200005];
int id[200005];
bool vis2[200005];
int cid[200005];
void dfs(int c, int p, int d) {
    int cnt = 0;
    par[c] = p;
    if(d != -1) id[c] = d;
    else id[c] = -1;
    vis2[c] = false;
    for(int n : adj[c]) {
        if(n==p || vis[n]) continue;
        if(d != -1) dfs(n, c, d);
        else dfs(n, c, cnt);
        cnt++;
    }
}
set<int> Col;
void dfs2(int c, int p, int d) {
    //cout << "dfs2 : "<< c << ' ' << p << ' ' <<d << '\n';
    if(cid[C[c]]==d) Col.insert(C[c]);
    for(int n : adj[c]) {
        if(n==p || vis[n]) continue;
        dfs2(n, c, d);//구현좃병싡장애니새기
    }
}
int DnC(int c) {
    //cout << c << ' ';
    if(Col.size()==0) return 1e9;
    assert(!vis[c]);
    get_sz(c, -1);
    int cen = get_cent(c, -1, sz[c]);
    dfs(cen, -1, -1);
    /*cout << "Dfs : "<< cen << '\n';
    cout << "Possible Color : ";
    for(int n : Col) cout << n <<' ';
    cout << '\n';*/
    set<int> S;
    int val = 1e9;
    vis[cen] = true;
    if(Col.find(C[cen])!=Col.end()) {
        set<int> S;
        queue<int> Q;
        bool isPos = true;
        S.insert(C[cen]);
        for(int n : B[C[cen]]) Q.push(n);
        while(!Q.empty()) {
            int c = Q.front();
            Q.pop();
            if(vis2[c]) continue;
            while(c != -1 && !vis2[c]) {
                if(Col.find(C[c])==Col.end()) {
                    isPos = false;
                    break;
                }
                if(S.find(C[c])==S.end()) {
                    S.insert(C[c]);
                    for(int n : B[C[c]]) Q.push(n);
                }
                vis2[c] = true;
                c = par[c];
            }
            if(!isPos) break;
        }
        if(isPos) val = min(val, (int)S.size()-1);
    }
    vector<set<int>> S2;
    int cnt = 0;
    for(int n : adj[cen]) {
        if(!vis[n]) cnt++;
    }
    for(int col : Col) {
        if(col == C[cen]) continue;
        int d = -3;
        for(int n : B[col]) {
            if(id[n]<0) {
                d = -3;
                break;
            }
            if(d==-3) d = id[n];
            else if(d !=-3 &&d != id[n]) d = -2;
        }
        cid[col] = d;
    }
    /*for(int i=0;i<N;i++) cout << id[i] << ' ';
    cout << '\n';
    for(int i=0;i<K;i++) cout << cid[i] << ' ';
    cout << '\n';*/
    cnt = 0;
    for(int n : adj[cen]) {
        if(!vis[n]) {
            Col = set<int> {};
            dfs2(n, -1, cnt);
            val = min(val, DnC(n));
            cnt++;
        }
    }
    //cout << cen << " : " << val <<'\n';
    return val;
}
signed main() {
    cin.sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> N >> K;
    int i, j;
    adj.resize(N);
    for(i=0;i<N-1;i++) {
        int a, b;
        cin >> a >> b;
        adj[a-1].push_back(b-1);
        adj[b-1].push_back(a-1);
    }
    B.resize(K);
    for(i=0;i<N;i++) {
        cin >> C[i];
        C[i]--;
        B[C[i]].push_back(i);
    }
    for(i=0;i<K;i++) {
        if(B[i].size()==1) {
            cout << "0";
            return 0;
        }
    }
    for(i=0;i<K;i++) Col.insert(i);
    cout << DnC(0);
}

Compilation message (stderr)

capital_city.cpp: In function 'int main()':
capital_city.cpp:129:12: warning: unused variable 'j' [-Wunused-variable]
  129 |     int i, j;
      |            ^

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