Codeforces/ice_skating.cpp at master · Jaskamalkainth/Codeforces · GitHub

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/*
 *    J1K7_7
 */
#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <cstring>
#include <list>
#include <map>
#include <unordered_map>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <utility>
#include <bitset>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <limits>
using namespace std;
typedef long long          ll;
typedef unsigned long long ull;
typedef long double        ld;
typedef pair<int,int>      pii;
typedef pair<ll,ll>        pll;
typedef vector<int>        vi;
typedef vector<long long>  vll;
#define left(x) 		   (x << 1)
#define right(x) 		   (x << 1) + 1
#define mid(l, r) 	       ((l + r) >> 1)
#define mp                 make_pair
#define pb                 push_back
#define all(a)             a.begin(),a.end()
#define debug(x)	       {cerr <<#x<<" = " <<x<<"\n"; }
#define debug2(x, y)       {cerr <<#x<<" = " <<x<<", "<<#y <<" = " <<y <<"\n";}
#define debug3(x, y, z)    {cerr <<#x<<" = " <<x<<", "<<#y <<" = " <<y <<", "<<#z<<" = "<<z<<"\n";}
#define debug4(x, y, z, w) {cerr <<#x<<" = " <<x<<", "<<#y <<" = " <<y <<", "<<#z<<" = "<<z<<", "<<#w << " = " <<w <<"\n";}
#define ss                 second
#define ff                 first
#define m0(x) 		       memset(x,0,sizeof(x))

const int mod=1e9+7;

template<class T> inline T gcd(T a,T b){ll t;while(b){a=a%b;t=a;a=b;b=t;}return a;}
template<class T> inline T lcm(T a,T b){return a/gcd(a,b)*b;}
template<typename T, typename S> T expo(T b, S e, const T &m){if(e <= 1)return e == 0?1: b;\
	return (e&1) == 0?expo((b*b)%m, e>>1, m): (b*expo((b*b)%m, e>>1, m))%m;}
template<typename T> T modinv(T a) { return expo(a, mod-2, mod); }

inline int nextint(){ int x; scanf("%d",&x); return x; }
inline ll nextll(){ ll x; scanf("%lld",&x); return x; }

const ll  mx_ll   = numeric_limits<ll> :: max();
const int mx_int  = numeric_limits<int> :: max();

const long double PI = (long double)(3.1415926535897932384626433832795);

struct point{
	int x,y;
}inp[101];
int vis[101];
vector<int> G[101];
inline void dfs(int u)
{
	vis[u] = 1;
	for(auto &v: G[u])
		if(!vis[v])
			dfs(v);
}

int main()
{
    ios_base::sync_with_stdio(false); cin.tie(0);
	int n; cin >> n;
	for(int i = 0; i < n; i++)
		cin >> inp[i].x >> inp[i].y;
	for(int i = 0; i < n; i++)
	{
		for(int j = i+1; j < n; j++)
		{
			if(inp[i].x == inp[j].x || inp[i].y == inp[j].y)
			{
				//add edge
				G[i].pb(j);
				G[j].pb(i);
			}
		}
	}
	int NCC = 0;
	for(int i = 0; i < n; i++)
		if(!vis[i])
		{
			dfs(i);
			NCC++;
		}

	cout << NCC-1 << "\n";

	return 0;
}