Submission #142821

#	Time	Username	Problem	Language	Result	Execution time	Memory
142821		cheetose	우호 조약 체결 (JOI14_friends)	C++11	100 / 100	116 ms	11900 KiB

friends

#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<vector>
#include<queue>
#include<bitset>
#include<string>
#include<stack>
#include<set>
#include<unordered_set>
#include<map>
#include<unordered_map>
#include<cstring>
#include<complex>
#include<cmath>
#include<iomanip>
#include<numeric>
#include<algorithm>
#include<list>
#include<functional>
#include<cassert>
#define mp make_pair
#define pb push_back
#define X first
#define Y second
#define y0 y12
#define y1 y22
#define INF 987654321987654321
#define PI 3.141592653589793238462643383279502884
#define fup(i,a,b,c) for(int (i)=(a);(i)<=(b);(i)+=(c))
#define fdn(i,a,b,c) for(int (i)=(a);(i)>=(b);(i)-=(c))
#define MEM0(a) memset((a),0,sizeof(a));
#define MEM_1(a) memset((a),-1,sizeof(a));
#define ALL(a) a.begin(),a.end()
#define SYNC ios_base::sync_with_stdio(false);cin.tie(0)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef double db;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int, int> Pi;
typedef pair<ll, ll> Pll;
typedef pair<ld, ld> Pd;
typedef vector<int> Vi;
typedef vector<ll> Vll;
typedef vector<double> Vd;
typedef vector<Pi> VPi;
typedef vector<Pll> VPll;
typedef vector<Pd> VPd;
typedef tuple<int, int, int> iii;
typedef tuple<int,int,int,int> iiii;
typedef tuple<ll, ll, ll> LLL;
typedef vector<iii> Viii;
typedef vector<LLL> VLLL;
typedef complex<double> base;
const ll MOD = 1000000007;
ll POW(ll a, ll b, ll MMM = MOD) {ll ret=1; for(;b;b>>=1,a=(a*a)%MMM)if(b&1)ret=(ret*a)% MMM; return ret; }
ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
ll lcm(ll a, ll b) { if (a == 0 || b == 0)return a + b; return a*(b / gcd(a, b)); }
int dx[] = { 0,1,0,-1,1,1,-1,-1 }, dy[] = { 1,0,-1,0,1,-1,1,-1 };

int parent[100001];
int find(int a)
{
	if (parent[a] < 0)return a;
	return parent[a] = find(parent[a]);
}
void merge(int a, int b)
{
	a = find(a), b = find(b);
	if (a != b)
	{
		parent[a] += parent[b];
		parent[b] = a;
	}
}
int n,m;
Vi v[100001];
bool chk[100001];
void dfs(int N)
{
	while(!v[N].empty())
	{
		int next=v[N].back();
		merge(N,next);
		v[N].pop_back();
		dfs(next);
	}
}
int main() {
	MEM_1(parent);
	scanf("%d%d",&n,&m);
	fup(i,1,m,1)
	{
		int x,y;
		scanf("%d%d",&x,&y);
		v[x].pb(y);
	}
	fup(i,1,n,1)
	{
		if(v[i].size()>=2)
		{
			for(int next:v[i])dfs(next);
		}
		fup(j,0,(int)v[i].size()-2,1)merge(v[i][j],v[i][j+1]);
	}
	ll ans=0;
	fup(i,1,n,1)
	{
		int t=find(i);
		if(chk[t])continue;
		int sz=-parent[t];
		if(sz>=2)ans+=1LL*sz*(sz-1);
		else ans+=v[t].size();
		chk[t]=1;
	}
	printf("%lld",ans);
}

Compilation message (stderr)

friends.cpp: In function 'int main()':
friends.cpp:93:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~
friends.cpp:97:8: 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: 30 / 30
• Subtask 3: 65 / 65