제출 #54068

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
54068		bogdan10bos	철인 이종 경기 (APIO18_duathlon)	C++14	23 / 100	135 ms	13236 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], cmp[100005];
int f[100005];
vector<int> edg[100005];

void DFS(int nod, int fth = 0)
{
    if(f[nod])  return;
    f[nod] = 1;
    if(fth == 0)    cmp[nod] = nod;
    else    cmp[nod] = cmp[fth];
    sz[nod] = 1;
    LL cnt = 0;
    for(auto nxt: edg[nod])
    {
        if(nxt == fth)  continue;
        DFS(nxt, nod);
        sz[nod] += sz[nxt];
    }
}

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

    scanf("%d%d", &N, &M);
    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);
    }

    for(int i = 1; i <= N; i++)
        if(!f[i])
            DFS(i);

    for(int i = 1; i <= N; i++)
    {
        int K = sz[ cmp[i] ];
        int nod = i;
        for(auto nxt: edg[nod])
        {
            if(sz[nxt] > sz[nod])   continue;
            ans += 1LL * sz[nxt] * (K - sz[nxt] - 1);
        }
        ans += 1LL * (K - sz[nod]) * (sz[nod] - 1);
    }

    printf("%lld\n", ans);

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

count_triplets.cpp: In function 'void DFS(int, int)':
count_triplets.cpp:22:8: warning: unused variable 'cnt' [-Wunused-variable]
     LL cnt = 0;
        ^~~
count_triplets.cpp: In function 'int main()':
count_triplets.cpp:38:10: 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);
         ~~~~~^~~~~~~~~~~~~~~~

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