Submission #199489

#	Time	Username	Problem	Language	Result	Execution time	Memory
199489		arnold518	우호 조약 체결 (JOI14_friends)	C++14	0 / 100	122 ms	6264 KiB

friends

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 1e5;

int N, M;
ll ans;
vector<int> adj[MAXN+10];

int par[MAXN+10], sz[MAXN+10];
int Find(int x) { return x==par[x] ? x : par[x]=Find(par[x]); }
void Union(int x, int y) { x=Find(x); y=Find(y); sz[y]+=sz[x]; par[x]=y; }

int main()
{
	int i, j;

	scanf("%d%d", &N, &M);
	for(i=1; i<=N; i++) par[i]=i, sz[i]=1;
	for(i=1; i<=M; i++)
	{
		int u, v;
		scanf("%d%d", &u, &v);
		adj[u].push_back(v);
	}
	for(i=1; i<=N; i++)
	{
		for(j=1; j<adj[i].size(); j++)
		{
			if(Find(adj[i][0])==Find(adj[i][j])) continue;
			Union(adj[i][0], adj[i][j]);
		}
	}

	//for(j=1; j<=N; j++)
	for(i=1; i<=N; i++)
	{
		for(auto it : adj[i])
		{
			int u=i, v=it;
			if(Find(u)!=Find(v) && sz[Find(u)]>1) Union(u, v);
		}
	}

	for(i=1; i<=N; i++)
	{
		for(auto it : adj[i])
		{
			int u=i, v=it;
			if(Find(u)!=Find(v)) ans++;
		}
	}

	for(i=1; i<=N; i++) if(i==Find(i)) ans+=(ll)sz[i]*(sz[i]-1);

	//for(i=1; i<=N; i++) printf("%d ", Find(i)); printf("\n");
	printf("%lld", ans);
}

Compilation message (stderr)

friends.cpp: In function 'int main()':
friends.cpp:32:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(j=1; j<adj[i].size(); j++)
            ~^~~~~~~~~~~~~~
friends.cpp:22:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &M);
  ~~~~~^~~~~~~~~~~~~~~~
friends.cpp:27:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &u, &v);
   ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 30
• Subtask 3: 0 / 65