Submission #1517701

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;  
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
#define rep(i,n) for(ll i=0;i<(n);i++)  
#define pii pair<int,int>
#define piii pair<int,pii>
#define mp make_pair
#define pb push_back  
#define ALL(a) (a).begin(),(a).end()
#define FST first
#define SEC second  
const int INF = (INT_MAX/2);
const ll LLINF = (LLONG_MAX/2);
const double eps = 1e-5;
const double PI = M_PI;  
#define DEB cout<<"!"<<endl
#define SHOW(a,b) cout<<(a)<<" "<<(b)<<endl
#define SHOWARRAY(ar,i,j) REP(a,i)REP(b,j)cout<<ar[a][b]<<((b==j-1)?((a==i-1)?("\n\n"):("\n")):(" "))
  
#define DIV 1000000007
typedef vector<ll> Array;
typedef vector<Array> matrix;

typedef tuple<int,int,int> tiii;
#define mt make_tuple

#define Nodes 100000
class UF{
public:
  int value[Nodes];
  int over[Nodes]; // When over < 0, 'over' keep elements of node(using negative number). -1 means this tree is a node.
  int root(int index){
    int t = index;
    while(over[t] >= 0)
      t = over[t];
    if(index!=t)over[index] = t;
    return t;
  }
  int merge(int a,int b){
    if(this->root(a) == this->root(b)) return false;
    over[root(a)] += over[root(b)];
    over[root(b)] = root(a);
  }
  UF(){rep(i,Nodes) over[i] = -1;}
};

int main(){
  UF u;
  int n,m; cin >> n >> m;
  rep(i,m){
    int a,b; cin >> a >> b;
    a--,b--;
    u.merge(a,b);
  }
  set<int> s;
  rep(i,n){
    s.insert(u.root(i));
  }
  cout << s.size() -1 << endl;
}

Submission Info

Judge Result