Submission #655320

#	Time	Username	Problem	Language	Result	Execution time	Memory
655320		600Mihnea	Inside information (BOI21_servers)	C++17	15 / 100	3595 ms	86272 KiB

servers

#include <bits/stdc++.h>

using namespace std;

const int N=240000+7;
int n;
int k;
vector<pair<int, int>> gg[N];
vector<pair<int,int>> q2[N];
vector<int> q1[N];

const int K = 20;
int p[N];
int pskip[K][N];
int dep[N];
int euler_tour[2 * N];
int tour_sz;
int first_time_on_tour[N];
int last_time_on_tour[N];
int lg2[2 * N];
int idup[N];
//vector<int> g[N];
pair<int, int> tab_lca[2 * N][K];

void dfs_lca(int a, int par = 0)
{
    p[a] = par;
    euler_tour[++tour_sz] = a;
    first_time_on_tour[a] = last_time_on_tour[a] = tour_sz;
    for (auto &it : gg[a])
    {
        int b=it.first;
        int i=it.second;

        if (b==par){
                continue;
        }
        idup[b]=i;
        dep[b] = 1 + dep[a];
        dfs_lca(b, a);
        euler_tour[++tour_sz] = a;
        last_time_on_tour[a] = tour_sz;
    }
}

void lcaTM()
{
    dfs_lca(1);
    for (int i = 2; i <= tour_sz; i++)
    {
        lg2[i] = 1 + lg2[i / 2];
    }
    for (int i = 1; i <= tour_sz; i++)
    {
        tab_lca[i][0] = {dep[euler_tour[i]], euler_tour[i]};
    }
    for (int k = 1; (1 << k) <= tour_sz; k++)
    {
        for (int i = 1; i + (1 << k) - 1 <= tour_sz; i++)
        {
            tab_lca[i][k] = min(tab_lca[i][k - 1], tab_lca[i + (1 << (k - 1))][k - 1]);
        }
    }
}

int lca(int a, int b)
{
    if (first_time_on_tour[a] > last_time_on_tour[b])
    {
        swap(a, b);
    }
    a = first_time_on_tour[a];
    b = last_time_on_tour[b];
    int k = lg2[b - a + 1];
    return min(tab_lca[a][k], tab_lca[b - (1 << k) + 1][k]).second;
}

int goup(int a,int cnt){
        assert(cnt>=0);
        for(int i=0;i<K;i++){
                if(cnt&(1<<i)){
                        a=pskip[i][a];
                }
        }
        return a;
}

int sol[N];
int tp[N];
int inc[N];
int dcr[N];

void dfs2(int a){
        inc[a]=max(inc[a],1);
        dcr[a]=max(dcr[a],1);
        for (auto &it:gg[a]){
                int b=it.first;
                if(b==p[a]){
                        continue;
                }
                if(idup[a]<idup[b]){
                        inc[b]=1+inc[a];
                }else{
                        dcr[b]=1+dcr[a];
                }
                dfs2(b);
        }
        ///cout<<"vis "<<a<<" : "<<inc[a]<<" vs "<<dcr[a]<<"\n";
}

int main() {
 ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
///        freopen("___input___.txt","r",stdin);

        cin>>n>>k;

        for(int i=1;i<=n+k-1;i++){
                string s;
                cin>>s;
                assert(s=="S"||s=="Q"||s=="C");
                if(s=="S"){
                        int a,b;
                        cin>>a>>b;
                        ///g[a].push_back(b);
                        ///g[b].push_back(a);
                        gg[a].push_back({b, i});
                        gg[b].push_back({a, i});
                        sol[i]=-1;
                }
                if(s=="Q"){
                        int a,b;
                        cin>>a>>b;
                        if(a==b){
                                tp[i]=1;
                                sol[i]=1;
                        }else{
                                q2[a].push_back({b, i});
                                tp[i]=1;
                                sol[i]=-2;
                        }
                }
                if(s=="C"){
                        int a;
                        cin>>a;
                        q1[a].push_back(i);
                        sol[i]=-3;
                }
        }

        lcaTM();
        dfs2(1);
        /// solve q1 for the general case

        for (int i=1;i<=n;i++){
                pskip[0][i]=p[i];
        }
        for (int k=1;k<K;k++){
                for (int i=1;i<=n;i++){
                        pskip[k][i]=pskip[k-1][pskip[k-1][i]];
                }
        }

        for (int a=1;a<=n;a++){
                for (auto &it:q2[a]){
                        int b=it.first,i=it.second;
                        /**

                        **/
                        /// drumul de la b la a e crescator?
                        vector<int> guys_x,guys_y;
                        int x=a,y=b,z;
                        swap(x,y);
                        z=lca(x,y);
                        int last=-1;
                        if(y!=z){
                                last=idup[y];
                        }else{
                               // cout<<"ici\n";
                                assert(x!=z);
                                assert(dep[x]-dep[z]-1>=0);
                             //   cout<<x << " : "<<dep[x]-dep[z]-1<<"\n";
                                int vlx=goup(x,dep[x]-dep[z]-1);
                                assert(p[vlx]==z);
                                last=idup[vlx];
                        }
                        bool ok2=1,ok2y=(inc[y]>=dep[y]-dep[z]);
                        ok2&=(dcr[x]>=dep[x]-dep[z]);
                        ///ok2&=(dcr[y]>=dep[z]-dep[y]);
                       /// cout<<" : "<<okx<<" vs "<<inc[x]<<" "<<dep[x]-dep[z]+1<<"\n";
                       int xx=x;
                        while (x!=z){
                                guys_x.push_back(idup[x]);
                                x=p[x];
                        }
                        while(y!=z){
                                guys_y.push_back(idup[y]);
                                y=p[y];
                        }

                        bool okx=1,oky=1;
                        for (int it=1;it<(int)guys_x.size();it++) {
                                okx&=(guys_x[it-1]<guys_x[it]);
                        }

                       /// cout<<okx<<" : "<<dcr[xx]<<" vs "<<dep[xx]-dep[z]<<"\n";
                        assert(okx==ok2);
                        for (int it=1;it<(int)guys_y.size();it++) {
                                oky&=(guys_y[it-1]>guys_y[it]);
                        }

                        assert(ok2y==oky);
                        vector<int> guys=guys_x;
                        reverse(guys_y.begin(),guys_y.end());
                        for (auto &V:guys_y){
                                guys.push_back(V);
                        }
                        bool ok=1;
                       /* cout<< " ---> ";
                        for (auto &it : guys){
                                cout<<it<<" ";
                        }
                        cout<<"\n";*/
                        assert(!guys.empty());
                        assert(guys.back()==last);
                        for (int it=1;it<(int)guys.size();it++){
                                ok&=(guys[it-1]<guys[it]);
                        }
                        bool ok3=okx&oky;
                        if(!guys_x.empty()&&!guys_y.empty()){
                                /// guys_x, guys_y
                                ok3&=(guys_x.back()<=guys_y[0]);
                        }
                        assert(ok3==ok);
                       /// cout<<" : " <<ok<<" "<<ok2<<"\n";
                        ///assert(ok==ok2);
                        ok&=(guys.back()<i);
                        sol[i]=ok;
                }
        }


        for (int i=1;i<=n+k-1;i++){
                if(tp[i]==1){
                        assert(sol[i]==0||sol[i]==1);
                        if(sol[i]==1){
                                cout<<"yes\n";
                        }else{
                                cout<<"no\n";
                        }
                }
        }

        return 0;
}

Compilation message (stderr)

servers.cpp: In function 'int main()':
servers.cpp:190:28: warning: unused variable 'xx' [-Wunused-variable]
  190 |                        int xx=x;
      |                            ^~

• Subtask 1: 2.5 / 2.5
• Subtask 2: 0 / 2.5
• Subtask 3: 2.5 / 2.5
• Subtask 4: 0 / 2.5
• Subtask 5: 0 / 5
• Subtask 6: 0 / 5
• Subtask 7: 10 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 12.5
• Subtask 10: 0 / 12.5
• Subtask 11: 0 / 17.5
• Subtask 12: 0 / 17.5