Submission #199501

#	Time	Username	Problem	Language	Result	Execution time	Memory
199501		arnold518	우호 조약 체결 (JOI14_friends)	C++14	100 / 100	169 ms	18064 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], adj2[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; }

bool vis[MAXN+10];

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(i=1; i<=N; i++)
	{
		for(auto it : adj[i])
		{
			int u=i, v=it;
			u=Find(u), v=Find(v);
			if(u!=v) adj2[u].push_back(v);//, printf("ADJ2 %d %d\n", u, v);
		}
	}
	set<pii, greater<pii>> S;
	vector<pii> V;
	for(i=1; i<=N; i++) if(i==Find(i)) S.insert({sz[i], i});

	while(!S.empty())
	{
		pii t=*S.begin(); S.erase(S.begin());
		if(t.first<=1) continue;
		//for(i=1; i<=N; i++) printf("%d ", Find(i)); printf("\n");
		//printf("NOW %d\n", t.second);
		//for(auto it : S) printf("S %d %d\n", it.first, it.second);
		for(auto nxt : adj2[t.second])
		{
			//printf("NXT / %d %d\n", sz[Find(nxt)], nxt);
			if(Find(t.second)!=Find(nxt)) V.push_back({t.second, nxt});
			if(S.find({sz[Find(nxt)], nxt})==S.end()) continue;
			S.erase({sz[Find(nxt)], nxt});
			S.insert({sz[Find(nxt)]+sz[Find(t.second)], nxt});
		}
	}
	for(auto it : V) if(Find(it.first)!=Find(it.second)) Union(it.first, it.second);

	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("%lld", ans);
}

Compilation message (stderr)

friends.cpp: In function 'int main()':
friends.cpp:34:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(j=1; j<adj[i].size(); j++)
            ~^~~~~~~~~~~~~~
friends.cpp:24:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &M);
  ~~~~~^~~~~~~~~~~~~~~~
friends.cpp:29:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &u, &v);
   ~~~~~^~~~~~~~~~~~~~~~

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