Submission #445741

#	Time	Username	Problem	Language	Result	Execution time	Memory
445741		cpp219	Duathlon (APIO18_duathlon)	C++14	49 / 100	2 ms	588 KiB

count_triplets

#pragma GCC optimization O2
#pragma GCC optimization "unroll-loop"
#pragma target ("avx2")

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define fs first
#define sc second
using namespace std;
typedef pair<ll,ll> LL;
const ll N = 2e3 + 9;
const ll Log2 = 20;
const ll inf = 1e9 + 7;

vector<ll> g[N],adj[N];
ll n,m,x,y,child[N],ans,sz,tin[N],Ntime = 1,low[N],bccs = 1;
stack<ll> st;

void DFS(ll u,ll p){
    //cout<<u<<" "<<p<<"\n";
    tin[u] = low[u] = Ntime; Ntime++; sz++;
    st.push(u);
    for (auto i : g[u]){
        if (i == p) continue;
        if (!tin[i]){
            DFS(i,u); low[u] = min(low[i],low[u]);
            if (low[i] >= tin[u]){
                adj[u].push_back(n + bccs);
                while(adj[n + bccs].empty() || adj[n + bccs].back() != i){
                    adj[n + bccs].push_back(st.top()); st.pop();
                }
                bccs++;
            }
        }
        else low[u] = min(low[u],tin[i]);
    }
}

void reDFS(ll node){
    child[node] = (node <= n);
    for (auto i : adj[node]){
        reDFS(i); child[node] += child[i];
        if (node > n) ans -= (ll) adj[node].size() * child[i] * (child[i] - 1);
    }
    if (node > n) ans -= (ll) adj[node].size() * (sz - child[node]) * (sz - child[node] - 1);
}

int main(){
    ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0);
    #define task "test"
    if (fopen(task".INP","r")){
        freopen(task".INP","r",stdin);
        //freopen(task".OUT","w",stdout);
    }
    cin>>n>>m;
    while(m--){
        cin>>x>>y;
        g[x].push_back(y); g[y].push_back(x);
    }
    for (ll i = 1;i <= n;i++){
        if (tin[i]) continue;
        sz = 0; DFS(i,i); //cout<<sz; return 0;
        ans += sz * (sz - 1) * (sz - 2);
        reDFS(i);
    }
    cout<<ans;
}

Compilation message (stderr)

count_triplets.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization O2
      | 
count_triplets.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
count_triplets.cpp:3: warning: ignoring '#pragma target ' [-Wunknown-pragmas]
    3 | #pragma target ("avx2")
      | 
count_triplets.cpp: In function 'int main()':
count_triplets.cpp:53:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   53 |         freopen(task".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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