Submission #912742

#	Time	Username	Problem	Language	Result	Execution time	Memory
912742		imarn	철인 이종 경기 (APIO18_duathlon)	C++14	0 / 100	1085 ms	1048576 KiB

count_triplets

#include<bits/stdc++.h>
#define f first
#define s second
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define pll pair<ll,ll>
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
#define vi vector<int>
#define vvi vector<vi>
using namespace std;
const int N=1e5+5;
vi g[N];stack<int>st;
vvi cmp,bst;
unsigned ll d[N]{0},lo[N]{0},t=0,ap[N]{0},id[N]{0},cur=0,isap[N]{0},sz[N],dp[N];
void dfs(int u,int p){
    lo[u]=d[u]=++t;st.push(u);
    for(auto v:g[u]){
        if(!d[v]){
            dfs(v,u);
            lo[u]=min(lo[u],lo[v]);
            if(d[u]<=lo[v]){
                ap[u] = (d[u]>1||d[v]>2);cmp.pb({u});
                while(cmp.back().back()!=v){
                    cmp.back().pb(st.top());st.pop();
                }
            }
        }
        else if(v!=p)lo[u]=min(lo[u],d[v]);
    }
}
void build(int n){
    for(int i=1;i<=n;i++)if(ap[i])id[i]=cur++,isap[id[i]]=1,bst.pb({}),sz[id[i]]=1;
    for(auto it : cmp){
        bst.pb({});sz[cur]=it.size();
        for(auto ij : it){
            if(!ap[ij])id[ij]=cur;
            else {
                bst[cur].pb(id[ij]);
                bst[id[ij]].pb(cur);
            }
        }cur++;
    }
}ll ans=0,n;
void solve(int u,int p){
    dp[u]=1;id[u]=1;
    ll tt=0;
    for(auto v:g[u]){
        if(v==p)continue;
        solve(v,u);
        if(isap[u])ans+=2*(dp[u]-1)*(dp[v]);
        dp[u]+=dp[v];
    }
    if(isap[u])ans+=2*(n-dp[u])*(dp[u]-1);
}
int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    int m;cin>>n>>m;
    for(int i=1;i<=m;i++){
        int u,v;cin>>u>>v;
        g[u].pb(v);g[v].pb(u);
    }
    //dfs(1,1);build(n);
    for(int i=1;i<=n;i++)sz[i]=1,isap[i]=1;
    for(int i=1;i<=n;i++)if(!id[i])solve(i,i);cout<<ans;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void solve(int, int)':
count_triplets.cpp:48:8: warning: unused variable 'tt' [-Wunused-variable]
   48 |     ll tt=0;
      |        ^~
count_triplets.cpp: In function 'int main()':
count_triplets.cpp:66:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   66 |     for(int i=1;i<=n;i++)if(!id[i])solve(i,i);cout<<ans;
      |     ^~~
count_triplets.cpp:66:47: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   66 |     for(int i=1;i<=n;i++)if(!id[i])solve(i,i);cout<<ans;
      |                                               ^~~~

• 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