Submission #866181

#	Time	Username	Problem	Language	Result	Execution time	Memory
866181		alexander707070	Duathlon (APIO18_duathlon)	C++14	0 / 100	1070 ms	32596 KiB

count_triplets

#include<bits/stdc++.h>
#define MAXN 200007
using namespace std;
 
long long n,m,a[MAXN],b[MAXN];
long long sz[MAXN],szcomp[MAXN],total[MAXN],rem[MAXN];
int comp[MAXN],k;
vector< pair<int,int> > v[MAXN];
vector<int> tree[MAXN];
 
long long ans,sum[MAXN];
 
int dep[MAXN],low[MAXN];
bool li[MAXN],bridge[MAXN];
 
void bcc(int x,int p,int d,int e){
 
    li[x]=true; dep[x]=d; low[x]=dep[x];
 
    for(int i=0;i<v[x].size();i++){
        if(!li[v[x][i].first]){
            bcc(v[x][i].first,x,d+1,v[x][i].second);
            low[x]=min(low[x],low[v[x][i].first]);
        }else if(v[x][i].first!=p){
            low[x]=min(low[x],dep[v[x][i].first]);
        }
    }
 
    if(p!=0 and low[x]==dep[x]){
        bridge[e]=true;
    }
}
 
void dfs(int x,int c){
    li[x]=true; comp[x]=c;
    szcomp[c]++;
 
    for(int i=0;i<v[x].size();i++){
        if(li[v[x][i].first] or bridge[v[x][i].second])continue;
        dfs(v[x][i].first,c);
    }
}

int num[MAXN],w,last[MAXN];

void dfs2(int x,int p){
    sz[x]=szcomp[x];

    w++; num[x]=w;

    sum[x]=szcomp[x]*(szcomp[x]-1);
 
    for(int i=0;i<tree[x].size();i++){
        if(tree[x][i]==p)continue;
 
        dfs2(tree[x][i],x);
        sz[x]+=sz[tree[x][i]];
        sum[x]+=sum[tree[x][i]];
    }

    last[x]=w;
}

int root[MAXN];
 
void dfs3(int x,int p,int t,int r){
    total[x]=t; root[x]=r;
 
    for(int i=0;i<tree[x].size();i++){
        if(tree[x][i]==p)continue;
        dfs3(tree[x][i],x,t,r);
    }
}

bool check(int x,int y){
    return num[y]>=num[x] and num[y]<=last[x];
}
 
int main(){
 
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
 
    cin>>n>>m;
    for(int i=1;i<=m;i++){
        cin>>a[i]>>b[i];
        v[a[i]].push_back({b[i],i});
        v[b[i]].push_back({a[i],i});
    }
 
    for(int i=1;i<=n;i++){
        if(!li[i])bcc(i,0,0,0);
    }
 
    for(int i=1;i<=n;i++)li[i]=false;
 
    for(int i=1;i<=n;i++){
        if(!li[i]){
            k++; dfs(i,k);
        }
    }
 
    for(int i=1;i<=m;i++){
        if(comp[a[i]]==comp[b[i]])continue;
 
        tree[comp[a[i]]].push_back(comp[b[i]]);
        tree[comp[b[i]]].push_back(comp[a[i]]);
    }
 
    for(int i=1;i<=k;i++){
        if(sz[i]==0){
            dfs2(i,0);
            dfs3(i,0,sz[i],i);
        }
    }
 
    for(int i=1;i<=m;i++){
        if(comp[a[i]]==comp[b[i]])continue;
        
        if(sz[comp[a[i]]]<sz[comp[b[i]]])swap(a[i],b[i]);
 
        rem[a[i]]+=sz[comp[b[i]]];
        rem[b[i]]+=total[comp[b[i]]]-sz[comp[b[i]]];
    }
    
    /*
    for(int i=1;i<=k;i++){
        ans+=( (total[i])*(total[i]-1) - sum[root[i]] - szcomp[i]*(total[i]-szcomp[i])*2 ) * szcomp[i];
 
        for(int f=0;f<tree[i].size();f++){
            if(sz[tree[i][f]]<sz[i]){
                ans-=(sz[tree[i][f]]*(sz[tree[i][f]]-1) - sum[tree[i][f]] )*szcomp[i];
            }else{
                ans-=( ( (total[i]-sz[i])*(total[i]-sz[i]-1) -  (sum[root[i]] - sum[i]) ) )*szcomp[i];
            }
        }
    }
    */

    for(int i=1;i<=n;i++){
        for(int f=1;f<=n;f++){
            for(int t=1;t<=n;t++){
                if(comp[i]==comp[f] or comp[f]==comp[t] or comp[i]==comp[t])continue;
                if(root[comp[i]]!=root[comp[f]] or root[comp[i]]!=root[comp[t]] or root[comp[f]]!=root[comp[t]])continue;

                ans++;

                for(int z:tree[comp[f]]){
                    if(sz[z]<sz[comp[f]] and check(comp[z],comp[i]) and check(comp[z],comp[t])){ans--; break;}
                    if(sz[z]>sz[comp[f]] and !check(comp[f],comp[i]) and !check(comp[f],comp[t])){ans--; break;}
                }
            }
        }
    }
 
    for(int i=1;i<=n;i++){
        ans+=(szcomp[comp[i]]-1)*(total[comp[i]]-szcomp[comp[i]]-rem[i])*2;
    }
 
    for(int i=1;i<=k;i++){
        ans+=szcomp[i]*(szcomp[i]-1)*(szcomp[i]-2);
    }
 
    cout<<ans<<"\n";
 
    return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void bcc(int, int, int, int)':
count_triplets.cpp:20:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |     for(int i=0;i<v[x].size();i++){
      |                 ~^~~~~~~~~~~~
count_triplets.cpp: In function 'void dfs(int, int)':
count_triplets.cpp:38:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |     for(int i=0;i<v[x].size();i++){
      |                 ~^~~~~~~~~~~~
count_triplets.cpp: In function 'void dfs2(int, int)':
count_triplets.cpp:53:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |     for(int i=0;i<tree[x].size();i++){
      |                 ~^~~~~~~~~~~~~~~
count_triplets.cpp: In function 'void dfs3(int, int, int, int)':
count_triplets.cpp:69:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   69 |     for(int i=0;i<tree[x].size();i++){
      |                 ~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10