Submission #1116905

#	Time	Username	Problem	Language	Result	Execution time	Memory
1116905		adaawf	Duathlon (APIO18_duathlon)	C++17	31 / 100	1128 ms	1048576 KiB

count_triplets

#include <iostream>
#include <vector>
#include <map>
using namespace std;
map<pair<int, int>, int> mm;
vector<int> g[100005], gg[200005];
int tin[100005], low[100005], dd[100005], da[100005], z = 0, db[100005];
long long int s[200005], f[200005], hh = 0, kk = 0, ha, res = 0;
void dfs(int x, int p) {
    tin[x] = low[x] = ++z;
    int fl = 0, c = 0;
    for (int w : g[x]) {
        if (w == p) continue;
        if (tin[w] == 0) {
            dfs(w, x);
            low[x] = min(low[x], low[w]);
            if (low[w] >= tin[x]) {
                fl = 1;
            }
            c++;
        }
        else low[x] = min(low[x], tin[w]);
    }
    if (p == -1) {
        if (c >= 2) dd[x] = 1;
    }
    else if (fl == 1) dd[x] = 1;
    hh += dd[x];
    kk++;
}
void dfs2(int x, int h) {
    da[x] = h;
    s[h]++;
    for (int w : g[x]) {
        if (da[w] != 0 || dd[w] == 1) continue;
        dfs2(w, h);
    }
}
void dfs3(int x, int p) {
    db[x] = 1;
    f[x] = s[x];
    for (int w : gg[x]) {
        if (w == p) continue;
        dfs3(w, x);
        f[x] += f[w];
    }
}
void dfs4(int x, int p) {
    long long int h = 0;
    for (int w : gg[x]) {
        if (w != p) dfs4(w, x);
        long long int k;
        if (w == p) k = ha - f[x];
        else k = f[w];
        res += s[w] * h * k;
        res += k * (s[w] - 1) * (s[w] - 1);
        res += s[w] * (s[w] - 1) / 2;
        h += k;
    }
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    long long int n, m;
    cin >> n >> m;
    for (int i = 1; i <= m; i++) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    for (int i = 1; i <= n; i++) {
        if (tin[i] == 0) {
            hh = kk = 0;
            dfs(i, -1);
            if (hh == 0) {
                res += kk * (kk - 1) * (kk - 2) / 2;
            }
        }
    }
    int zz = 0;
    for (int i = 1; i <= n; i++) {
        if (dd[i] == 1) {
            da[i] = ++zz;
            s[zz] = 1;
            for (int w : g[i]) {
                if (da[w] == 0 && dd[w] == 0) {
                    zz++;
                    dfs2(w, zz);
                }
            }
        }
    }
    for (int i = 1; i <= zz; i++) {
        res += s[i] * (s[i] - 1) * (s[i] - 2) / 2;
    }
    for (int i = 1; i <= n; i++) {
        for (int w : g[i]) {
            int h = da[i], k = da[w];
            if (h == k || mm.count({h, k})) continue;
            gg[h].push_back(k);
            mm[{h, k}] = 1;
        }
    }
    for (int i = 1; i <= zz; i++) {
        if (db[i] == 0) {
            dfs3(i, -1);
            ha = f[i];
            dfs4(i, -1);
        }
    }
    cout << res * 2;
}

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