Submission #926254

#	Time	Username	Problem	Language	Result	Execution time	Memory
926254		asdasdqwer	Duathlon (APIO18_duathlon)	C++14	0 / 100	112 ms	29120 KiB

count_triplets

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

#define int int64_t

signed main() {
    int n,m;cin>>n>>m;
    vector<vector<int>> g(n);
    for (int i=0;i<m;i++) {
        int a,b;cin>>a>>b;a--;b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }

    vector<vector<int>> cmp;
    stack<int> st;
    vector<int> low(n, 1e9), num(n, 1e9);
    vector<bool> isart(n, false);
    int timer=0;

    function<void(int,int)> dfs=[&](int node, int pv) {
        low[node] = num[node] = timer++;
        st.push(node);
        for (int x:g[node]) {
            if (x == pv) {
                continue;
            }

            if (num[x] == (int)1e9) {
                dfs(x, node);
                low[node] = min(low[node], low[x]);

                if (low[x] >= num[node]) {
                    isart[node] = true;
                    cmp.push_back({});
                    while (st.top() != node) {
                        cmp[cmp.size()-1].push_back(st.top());
                        st.pop();
                    }
                    cmp[cmp.size()-1].push_back(node);
                }
            }

            else {
                low[node] = min(low[node], num[x]);
            }
        }
    };

    for (int i=0;i<n;i++) {
        if (num[i] == (int)1e9)dfs(i, -1); 
    }

    int nn = n + cmp.size();
    vector<vector<int>> ng(nn);
    for (int i=0;i<cmp.size();i++) {
        for (int x:cmp[i]) {
            ng[x].push_back(i+n);
            ng[i+n].push_back(x);
        }
    }

    vector<bool> vis(nn, false);
    vector<int> sz(nn, -1);

    function<int(int)> dfs2=[&](int node) -> int {
        vis[node] = true;
        int ans = 0;
        if (node < n) ans++;
        for (int x:ng[node]) {
            if (!vis[x]) ans += dfs2(x);
        }
        return ans;
    };

    for (int i=0;i<nn;i++) {
        if (!vis[i]) {
            sz[i] = dfs2(i);
        }
    }

    vis.assign(n, false);
    
    int tmpAns = 0, ans = 0;
    function<int(int, int)> dfs3=[&](int node, int pv)-> int {
        int sms = 0, smsSquare = 0;
        for (int x:ng[node]) {
            if (x == pv)continue;
            int res = dfs3(x, node);
            sms += res;
            smsSquare += res * (res - 1);
        }

        if (node < n && isart[node]) {
            ans -= smsSquare;
            ans -= (tmpAns - sms) * (tmpAns - sms - 1);
        }

        return sms + (node < n);
    };

    for (int i=0;i<nn;i++) {
        if (sz[i] == -1) continue;
        tmpAns = sz[i];
        ans += tmpAns * (tmpAns - 1) * (tmpAns - 2);
        dfs3(i, -1);
    }

    cout<<ans<<"\n";
}

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:56:19: warning: comparison of integer expressions of different signedness: 'int64_t' {aka 'long int'} and 'std::vector<std::vector<long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |     for (int i=0;i<cmp.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