Submission #49633

#	Time	Username	Problem	Language	Result	Execution time	Memory
49633		SpaimaCarpatilor	Duathlon (APIO18_duathlon)	C++17	100 / 100	287 ms	29480 KiB

count_triplets

#include<bits/stdc++.h>

using namespace std;

int nodes, N, M, lev[100009], dp[100009], vol[200009], papa[200009], compSize[200009];
long long sumProd[200009];
stack < pair < int, int > > stk;
vector < int > v[100009], h[200009];

void addComp (pair < int, int > whenToStop)
{
    pair < int, int > curr;
    vector < int > currComp;
    do {
        curr = stk.top ();
        stk.pop ();
        currComp.push_back (curr.first);
        currComp.push_back (curr.second);
    }while (curr != whenToStop);
    sort (currComp.begin (), currComp.end ());
    currComp.erase (unique (currComp.begin (), currComp.end ()), currComp.end ());
/*    for (auto it : currComp)
        printf ("%d ", it);
    printf ("\n");*/
    nodes ++;
    for (auto it : currComp)
        h[it].push_back (nodes),
        h[nodes].push_back (it);
}

void dfs (int nod, int tata)
{
    dp[nod] = lev[nod];
    for (auto it : v[nod])
        if (lev[it] == 0)
        {
            lev[it] = lev[nod] + 1;
            stk.push ({it, nod});
            dfs (it, nod);
            if (dp[it] < dp[nod])
                dp[nod] = dp[it];
            if (dp[it] >= lev[nod])
                addComp ({it, nod});
        }
    for (auto it : v[nod])
        if (it != tata)
        {
            if (lev[it] < dp[nod])
                dp[nod] = lev[it];
        }
}

vector < int > currComp;
void init (int nod, int tata)
{
    currComp.push_back (nod);
    vol[nod] = (nod <= N), papa[nod] = tata;
    int sum = 0;
    for (auto it : h[nod])
        if (it != tata)
            init (it, nod), vol[nod] += vol[it],
            sumProd[nod] += 1LL * sum * vol[it],
            sum += vol[it];
}

namespace treeSubtask {
    int vol[100009];
    void dfs (int nod, int tata)
    {
        vol[nod] = 1;
        for (auto it : v[nod])
            if (it != tata)
                dfs (it, nod), vol[nod] += vol[it];
    }
    long long solveTree ()
    {
        dfs (1, -1);
        long long ans = 0;
        for (int x=1; x<=N; x++)
        {
            int sum = 0;
            for (auto it : v[x])
            {
                int currSize = 0;
                if (vol[it] > vol[x]) currSize = N - vol[x];
                else currSize = vol[it];
                ans += 1LL * sum * currSize;
                sum += currSize;
            }
        }
        return ans * 2LL;
    }
};

void buildBiconnectedTree ()
{
    nodes = N;
    for (int i=1; i<=N; i++)
        if (lev[i] == 0)
            lev[i] = 1, dfs (i, -1);
}

void read ()
{
    scanf ("%d %d", &N, &M);
    while (M --)
    {
        int x, y;
        scanf ("%d %d", &x, &y);
        v[x].push_back (y);
        v[y].push_back (x);
    }
}

void precalc ()
{
    for (int i=1; i<=N; i++)
        if (vol[i] == 0)
        {
            currComp.clear (), init (i, -1);
            for (auto nod : currComp)
                sumProd[nod] += 1LL * (vol[nod] - (nod <= N)) * (vol[i] - vol[nod]),
                sumProd[nod] <<= 1LL, compSize[nod] = vol[i];
        }
}

int main ()
{
//freopen ("input", "r", stdin);
//freopen ("output", "w", stdout);

read ();
buildBiconnectedTree ();
precalc ();
long long ans = 0;
for (int x=1; x<=N; x++)
{
    long long before = ans;
    ans += sumProd[x];
    for (auto comp : h[x])
    {
        ans += sumProd[comp];
        if (papa[comp] == x)
            ans -= 2LL * (compSize[x] - vol[comp]) * vol[comp];
        else
            ans -= 2LL * (compSize[x] - vol[x]) * vol[x];
    }
}
printf ("%lld\n", ans);
return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:138:15: warning: unused variable 'before' [-Wunused-variable]
     long long before = ans;
               ^~~~~~
count_triplets.cpp: In function 'void read()':
count_triplets.cpp:105:11: 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:109:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf ("%d %d", &x, &y);
         ~~~~~~^~~~~~~~~~~~~~~~~

• 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