Submission #971445

#	Time	Username	Problem	Language	Result	Execution time	Memory
971445		asdasdqwer	Village (BOI20_village)	C++14	100 / 100	229 ms	53968 KiB

Village

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

#define int int64_t

pair<int, vector<int>> big(int n, vector<vector<int>> &g) { 
    vector<int> v;
    vector<int> d(n, 0);
    vector<vector<int>> lft(n, vector<int>(20, -1));
    function<void(int,int)> dfs=[&](int node, int p) {
        v.push_back(node);
        for (int x:g[node]) {
            if (x==p)continue;
            d[x]=d[node]+1;
            lft[x][0]=node;
            dfs(x, node);
        }
    };
 
    dfs(0, -1);
    
    for (int j=1;j<20;j++) {
        for (int i=0;i<n;i++) {
            lft[i][j] = lft[i][j-1];
            if (lft[i][j] != -1) {
                lft[i][j] = lft[lft[i][j]][j-1];
            }
        }
    }
    vector<int> idx(n, -1);
    for (int i=0;i<n;i++) {
        idx[v[i]]=i;
    }
 
    vector<int> out(n);
    for (int i=0;i<n;i++) {
        out[i] = v[(idx[i] + n/2) % n];
    }
    
    long long dist = 0;
 
    auto jmp=[&](int a, int steps) {
        int cnt=0;
        while (steps) {
            if ((steps&1)==1) {
                a = lft[a][cnt];
            }
            cnt++;
            steps>>=1;
        }
        return a;
    };
 
    auto lca=[&](int a, int b) {
        if (d[a] < d[b])swap(a,b);
        int ret = d[a]-d[b];
        a = jmp(a, d[a]-d[b]);
        if (a == b) return ret;
 
        for (int i=19;i>=0;i--) {
            if (lft[a][i] != lft[b][i]) {
                a = lft[a][i];
                b = lft[b][i];
                ret += (1<<(i+1));
            }
        }
 
        return ret+2;
    };
 
    for (int i=0;i<n;i++) {
        dist += lca(i, out[i]);
    }
 
    return make_pair(dist, out);
}



signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;cin>>n;
    vector<set<int>> g(n);
    vector<vector<int>> bck(n);
    vector<int> dg(n,0);
    for (int i=1;i<n;i++) {
        int a,b;cin>>a>>b;a--;b--;
        g[a].insert(b);
        g[b].insert(a);
        bck[a].push_back(b);
        bck[b].push_back(a);
        dg[a]++;dg[b]++;
    }

    queue<int> q;
    vector<bool> vis(n, false);
    for (int i=0;i<n;i++) {
        if (dg[i]==1){
            q.push(i);
            vis[i]=true;
        }
    }
    
    int ans=0;
    vector<int> conf(n,0);
    for (int i=0;i<n;i++) {
        conf[i]=i;
    }
    
    vector<bool> swp(n, false);
    
    while (!q.empty()) {
        int t=q.front();q.pop();
        if (g[t].size() == 0) {
            if (!swp[conf[t]]) {
                swap(conf[t], conf[bck[t][0]]);
                swp[conf[t]]=true;
                ans += 2;
            }
            continue;
        }
    
        int ne = *g[t].begin();
        vis[ne]=true;
    
        if (g[ne].find(t) != g[ne].end()) g[ne].erase(g[ne].find(t));
        for (int x:g[ne]) {
            if (g[x].find(ne) != g[x].end()) g[x].erase(g[x].find(ne));
            dg[x]--;
            if (dg[x]<=1 && !vis[x]) {
                q.push(x);
                vis[x]=true;
            }
        }
        if (!swp[ne] && !swp[t]) {
            dg[ne]--;
            ans+=2;
            swap(conf[ne], conf[t]);
            swp[ne]=swp[t]=true;
        }
    }

    auto [ans2, out] = big(n, bck);
    
    cout<<ans<<" "<<ans2<<"\n";
    for (int x:conf) {
        cout<<x+1<<" ";
    }
    cout<<"\n";

    for (int x:out) {
        cout<<x+1<<" ";
    }
    cout<<"\n";
}

Compilation message (stderr)

Village.cpp: In function 'int main()':
Village.cpp:144:10: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  144 |     auto [ans2, out] = big(n, bck);
      |          ^

• Subtask 1: 12 / 12
• Subtask 2: 38 / 38
• Subtask 3: 50 / 50