Submission #49156

#	Time	Username	Problem	Language	Result	Execution time	Memory
49156		ainta	Duathlon (APIO18_duathlon)	C++17	100 / 100	379 ms	44412 KiB

count_triplets

#include<cstdio>
#include<algorithm>
#include<vector>
#define N_ 201000
using namespace std;
int n, m, Num[N_], cnt, chk[N_], Up[N_], BC, C[N_], nn;
vector<int>E[N_], Ch[N_], G[N_];
void DFS(int a) {
    nn++;
    Num[a] = ++cnt;
    Up[a] = cnt;
    for (auto &x : E[a]) {
        if (Num[x]) {
            Up[a] = min(Up[a], Num[x]);
            continue;
        }
        DFS(x);
        Ch[a].push_back(x);
        if (Up[x] >= Num[a]) {
            chk[x] = 1;
        }
        Up[a] = min(Up[a], Up[x]);
    }
}
void Add_Edge(int a, int b) {
    G[a].push_back(b);
    G[b].push_back(a);
}
void Make_BCC(int a, int b) {
    if(b!=0){
        Add_Edge(a, b);
    }
    for (auto x : Ch[a]) {
        if (chk[x]) {
            BC++;
            Add_Edge(a, BC);
            Make_BCC(x, BC);
        }
        else {
            Make_BCC(x, b);
        }
    }
}
long long r1, r2, r3, SS[N_];
void Calc(int a, int pp) {
    if (a <= n)C[a] = 1;
    for (auto &x : G[a]) {
        if (x == pp)continue;
        Calc(x, a);
        C[a] += C[x];
    }
    vector<int>T;
    for (auto &x : G[a]) {
        if (x != pp)T.push_back(C[x]);
        else T.push_back(nn - C[a]);
    }
    for (auto &t : T) SS[a] += 1ll * t*(t-1);
}
void Go(int a, int pp) {
    for (auto &x : G[a]) {
        if (x == pp)continue;
        Go(x, a);
    }
    if (a > n)return;
    long long s = 1ll * (nn - 1)*(nn - 2);
    for (auto &x : G[a]) {
        long long t;
        if (x == pp) {
            t = SS[x] - 1ll * C[a] * (C[a]-1);
        }
        else {
            t = SS[x] - 1ll * (nn - C[x])*(nn - C[x]-1);
        }
        s -= t;
    }
    r2 += s;
}
int main() {
    int i, a, b;
    scanf("%d%d", &n, &m);
    for (i = 0; i < m; i++) {
        scanf("%d%d", &a, &b);
        E[a].push_back(b);
        E[b].push_back(a);
    }
    BC = n;
    for (i = 1; i <= n; i++) {
        if (!Num[i]) {
            nn = 0;
            DFS(i);
            Make_BCC(i, 0);
            Calc(i, 0);
            Go(i, 0);
        }
    }
    printf("%lld\n", r2 );
    return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:80:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~
count_triplets.cpp:82:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~

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