Submission #54061

#	Time	Username	Problem	Language	Result	Execution time	Memory
54061		bogdan10bos	Duathlon (APIO18_duathlon)	C++14	0 / 100	103 ms	13268 KiB

count_triplets

#include <bits/stdc++.h>

using namespace std;

//#define FILE_IO

typedef long long LL;

LL ans;
int N, M;
int sz[100005];
int f[100005];
vector<int> edg[100005];

void DFS(int nod, int fth)
{
    sz[nod] = 1;
    LL cnt = 0;
    for(auto nxt: edg[nod])
    {
        if(nxt == fth)  continue;
        DFS(nxt, nod);
        sz[nod] += sz[nxt];
        ans += 1LL * sz[nxt] * cnt;
        cnt += sz[nxt];
    }
    ans += 1LL * (N - sz[nod]) * (sz[nod] - 1);
}

int main()
{
    #ifdef FILE_IO
    freopen("1.in", "r", stdin);
    freopen("1.out", "w", stdout);
    #endif

    scanf("%d%d", &N, &M);
    assert(M == N - 1);
    for(int i = 1; i <= M; i++)
    {
        int x, y;
        scanf("%d%d", &x, &y);
        edg[x].push_back(y);
        edg[y].push_back(x);
    }

    DFS(1, 0);

    ans *= 2;
    printf("%lld\n", ans);

    return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:37:10: 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:42:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &x, &y);
         ~~~~~^~~~~~~~~~~~~~~~

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