Submission #261167

#	Time	Username	Problem	Language	Result	Execution time	Memory
261167		Hideo	Duathlon (APIO18_duathlon)	C++17	23 / 100	211 ms	17252 KiB

count_triplets

//1610612741, 1000000007
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//#pragma GCC optimization ("O3")
//#pragma GCC optimization ("unroll-loops")
//#pragma GCC optimize ("Ofast")
//#pragma GCC target ("avx,avx2,fma")

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

#define all(s) s.begin(), s.end()
#define ok puts("ok")
#define ll long long
#define pb push_back
#define mk make_pair
#define fr first
#define sc second
#define vi vector < int >
#define pi pair < int, int >
#define pii pair < int, pi >
#define next next123
#define left left123

const int N = 2e5 + 7;
const int INF = 1e9 + 7;

ll S1, S2, S3, S4;
int h[N], d[N], sz[N], mn[N], flg[N];
int n, m, csz;

vi g[N];

void precalc (int v, int p = 0){
    h[v] = h[p] + 1;
    sz[v] = 1;
    for (int to : g[v]){
        if (!h[to]){
            precalc(to, v);
            sz[v] += sz[to];
        }
    }
}

void calc1 (int v){
    for (int to : g[v]){
        if (h[to] - h[v] == 1){
            calc1(to);
            S1 += 1LL * (csz - sz[to] - 1) * sz[to];
        }
    }
    S1 += 1LL * (csz - sz[v]) * (sz[v] - 1);
}

int calc2 (int v){
    mn[v] = h[v];
    int c = 0;
    for (int to : g[v]){
        if (h[to] - h[v] == 1){
            c += calc2(to);
            mn[v] = min(mn[v], mn[to]);
        }
        else
            mn[v] = min(mn[v], h[to]);
    }
    S2 += 1LL * c * (csz - sz[v]);
    c -= d[h[v]];
    if (mn[v] + 1 < h[v]){
        d[mn[v] + 1]++;
        c++;
    }
    return c;
}

bool comp (int a, int b){
    return mn[a] > mn[b];
}

void calc3 (int v){
    for (int to : g[v]){
        if (h[to] - h[v] == 1){
            flg[v] = 1;
            S3 += 1LL * sz[to] * ((h[v] - mn[v] - 1) * (h[v] - mn[v]) -
                                  (h[v] - mn[to] - 1) * (h[v] - mn[to])) / 2;
            calc3(to);
        }
    }
    if (!flg[v])
        S3 += 1LL * (h[v] - mn[v] - 1) * (h[v] - mn[v]) / 2;
    sort(all(g[v]), comp);
}

void calc4 (int v){
    int s = 0;
    for (int to : g[v]){
        if (h[to] - h[v] == 1){
            if (mn[to] < h[v])
                S4 += 1LL * (h[v] - mn[to]) * s;
            s += sz[to];
            calc4(to);
        }
    }
}

main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> m;
    for (int i = 1; i <= m; i++){
        int a, b;
        cin >> a >> b;
        g[a].pb(b);
        g[b].pb(a);
    }
    for (int i = 1; i <= n; i++)
        if (!h[i])
            precalc(i);
    for (int i = 1; i <= n; i++){
        if (h[i] == 1){
            csz = sz[i];
            calc1(i);
            calc2(i);
            calc3(i);
            calc4(i);
        }
    }
    cout << S1 + 2LL * (S2 + S3 + S4);
}

Compilation message (stderr)

count_triplets.cpp:104:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 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