Submission #372729

#	Time	Username	Problem	Language	Result	Execution time	Memory
372729		BartolM	Duathlon (APIO18_duathlon)	C++17	31 / 100	133 ms	20452 KiB

count_triplets

#include <bits/stdc++.h>

using namespace std;

#define X first
#define Y second
#define mp make_pair
#define pb push_back
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <int, pii> pip;
typedef pair <pii, int> ppi;
typedef pair <ll, ll> pll;

const int INF=0x3f3f3f3f;
const int N=1e5+5;

int n, m, dtime=1;
ll sol=0;
int cnt[N], siz[N], P[N], sweep[N];
int dt[N], lw[N];
vector <int> ls[N], ls2[N];
vector <pii> ed;
#define DEBUG 0

int name(int x) {
    if (x==P[x]) return x;
    P[x]=name(P[x]);
    return P[x];
}

void mrg(int a, int b) {
    a=name(a); b=name(b);
    if (a==b) return;
    P[a]=b;
    siz[b]+=siz[a];
}

void rek(int node, int par) {
    dt[node]=dtime++;
    lw[node]=dt[node];
    for (int sus:ls[node]) {
        if (sus==par) continue;
        if (dt[sus]==0) {
            rek(sus, node);
            lw[node]=min(lw[node], lw[sus]);
        }
        else { //backedge
            lw[node]=min(lw[node], dt[sus]);
            sweep[node]++; sweep[sus]--;
        }
    }
    if (par && lw[node]==dt[node]) { //bridge
        ed.pb(mp(node, par));
        #if DEBUG
            printf("bridge %d -> %d\n", node, par);
        #endif
    }
    else if (par) {
        mrg(node, par);
        #if DEBUG
            printf("mrgam %d i %d\n", node, par);
        #endif
    }
//    sweep[par]+=sweep[node];
//    if (sweep[node]) mrg(node, par);
}

void dfs(int node, int par) {
    cnt[node]=siz[node];
    for (int sus:ls2[node]) {
        if (sus==par) continue;
        dfs(sus, node);
        cnt[node]+=cnt[sus];
    }
}

void calc(int node, int par, int uk) {
    sol+=(ll)siz[node]*(siz[node]-1)*(siz[node]-2);
    int iz=uk-siz[node];
    for (int sus:ls2[node]) {
        if (sus==par) continue;
        calc(sus, node, uk);
        iz-=cnt[sus];
        sol+=(ll)cnt[sus]*(uk-cnt[sus]-siz[node]);


        if (siz[node]>2) sol+=(ll)cnt[sus]*(siz[node]-1)*(siz[node]-1)*2;
    }
    sol+=(ll)iz*(uk-iz-siz[node]);
//    printf("node: %d, iz: %d\n", node, iz);
    if (siz[node]>2) sol+=(ll)iz*(siz[node]-1)*(siz[node]-1)*2;
}

void solve() {
    for (int i=1; i<=n; ++i) P[i]=i, siz[i]=1;
    for (int i=1; i<=n; ++i) {
        if (dt[i]) continue;
        dtime=1;
        ed.clear();
        rek(i, 0);
        for (pii pp:ed) {
            ls2[name(pp.X)].pb(name(pp.Y));
            ls2[name(pp.Y)].pb(name(pp.X));
        }
    }

    for (int i=1; i<=n; ++i) {
        sort(ls2[i].begin(), ls2[i].end());
        ls2[i].erase(unique(ls2[i].begin(), ls2[i].end()), ls2[i].end());

        #if DEBUG
            printf("node: %d, siz: %d, sus: ", i, siz[i]);
            for (int sus:ls2[i]) printf("%d ", sus);
            printf("\n");
        #endif // DEBUG
    }

    for (int i=1; i<=n; ++i) {
        if (cnt[i] || P[i]!=i) continue;
        dfs(i, 0);
        calc(i, 0, cnt[i]);
    }
    printf("%lld\n", sol);
}

void load() {
    scanf("%d %d", &n, &m);
    for (int i=0; i<m; ++i) {
        int a, b;
        scanf("%d %d", &a, &b);
        ls[a].pb(b); ls[b].pb(a);
    }
}

int main() {
    load();
    solve();
    return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void load()':
count_triplets.cpp:128:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  128 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
count_triplets.cpp:131:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  131 |         scanf("%d %d", &a, &b);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• 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