Language: C++

#include <iomanip>
#include <iostream>
#include <algorithm>
#include <bitset>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <map>
#include <stack>
#include <queue>
#include <unordered_map>
#include <utility>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <cstdio>
#include <math.h>
#include <stdio.h>
#include <deque>
#include <numeric>
#include <array>

using namespace std;

#define REP(i,from,to) for( long long int i = (from); i < (to); i++ )
#define REV(v) for (auto itr = v.rbegin(); itr != v.rend(); itr++)
#define ll long long
#define ALL(a) (a).begin(), (a).end()
#define SORT(v) sort( ALL(v) );
#define LAST(v) v[v.size()-1]
#define ZERO(a) memset(a,0,sizeof(a));
#define MINUS(a) memset(a,-1,sizeof(a));
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define pi pair<int, int>
#define MP make_pair
#define PB push_back
#define EB emplace_back
#define IIN(a) int a; cin >> a;
#define LIN(a) ll a; cin >> a;
#define SIN(a) string a; cin >> a;
#define VL(v,n) vector<ll> v(n);
#define Read_VL(v,n) vector<ll> v(n);REP(i,0,n)cin>>v[i];
#define sumV(v,n) Vl(acm,n) REP(i,0,n) acm[i] = v[i] + ( i == 0 ? 0 : acm[i - 1]);
#define EPS (1e-10)
#define INF 1000000000000LL

void YN(bool b){cout<<(b?"YES":"NO")<<"\n";}
void Yn(bool b){cout<<(b?"Yes":"No")<<"\n";}
void yn(bool b){cout<<(b?"yes":"no")<<"\n";}

template<class S>S max(vector<S>&a){return *max_element(all(a));}
template<class S>S min(vector<S>&a){return *min_element(all(a));}

template<class T>void puta(T&&t){cout<<t<<"\n";}
template<class H,class...T>void puta(H&&h,T&&...t){cout<<h<<' ';puta(t...);}


template <typename ELEMENT_TYPE>
struct _setfillw {
    ELEMENT_TYPE c;
    std::streamsize w;
    _setfillw(ELEMENT_TYPE c, std::streamsize w) : w(w), c(c) {}
};

template <typename ELEMENT_TYPE>
inline _setfillw<ELEMENT_TYPE> setfillw(ELEMENT_TYPE c, std::streamsize w) {
    return _setfillw<ELEMENT_TYPE>(c, w);
}

template <typename ELEMENT_TYPE>
inline std::ostream& operator << (std::ostream& os, const _setfillw<ELEMENT_TYPE>& manip)
{
    return os << std::setw(manip.w) << std::setfill(manip.c);
}

template<class T=ll>struct Graph{
	int n;
	vector<vector<tuple<ll,T>>>edge;
	Graph(int N=1):n(N){edge.resize(n);}
	void add(ll f,ll t,T c,bool d=false){
		edge[f].emplace_back(t,c);
		if(!d)edge[t].emplace_back(f,c);
	}
	void view(){
		REP(i,0,n)for(auto&e:edge[i])
			puta(i,"=>",get<0>(e),", cost :",get<1>(e));
	}
};


bool length_cmp( string &a, string &b ){
  return a.size() < b.size();
}

ll StoLL( string s )
{
	ll num=0;
  REP( i, 0, s.size() ){
    num = num * 10 + ( s[i] ^ 48 );
  }
  return num;
}

ll CtoLL( char c )
{
	if( 'a' <= c && c <= 'z'){
		return (ll)( c ^ 96 ) ;
	}
	else if( 'A' <= c && c <= 'Z'){
		return (ll)( c ^ 64 );
	}
  return 0;
}

ll MOD=1000000007;
ll dx[4] = { 1, 0, -1, 0 };
ll dy[4] = { 0, 1, 0, -1 };


#include <numeric>
#include <array>

struct UF{
  vector<ll> par,sz;
  UF(){}
  UF(ll n): par(n), sz(n, 1){
    iota( par.begin(), par.end(), 0 );
  }
  ll find( ll x ){
    if( x == par[x] )return x;
    return par[x] = find( par[x] );
  }
  void unite( ll x, ll y ){
    x = find( x ); y = find( y );
    if( x == y ) return;
    if( sz[x] < sz[y] ) swap( x, y );
    sz[x] += sz[y];
    par[y] = x;
  }
  bool same( ll x, ll y ){
    return find( x ) == find( y );
  }
};

signed main(){
  LIN(n) LIN(m)
  UF uf(n)
  vector<ll> ans(n), a(n), b(n);
  REP( i, 0, m ){
    cin >> a[i] >> b[i];
    a[i]--;b[i]--;
  }
  ans[m - 1] = n * (n - 1) / 2;
  for( ll i = m - 1; i >= 1; i-- ){
    if( uf.same( a[i], b[i] ) ){
      ans[i - 1] = ans[i];
    }else{
      ll p = uf.sz[uf.find( a[i] ) ];
      ll q = uf.sz[uf.find( b[i] ) ];
      uf.unite( a[i], b[i] );
      ans[i - 1] = ans[i] - p * q;
    }
  }
  REP( i, 0, ans.size() ){
    puta( ans[i] );
  }
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:150:3: error: expected ',' or ';' before 'vector'
  150 |   vector<ll> ans(n), a(n), b(n);
      |   ^~~~~~
a.cc:152:12: error: 'a' was not declared in this scope
  152 |     cin >> a[i] >> b[i];
      |            ^
a.cc:152:20: error: 'b' was not declared in this scope
  152 |     cin >> a[i] >> b[i];
      |                    ^
a.cc:155:3: error: 'ans' was not declared in this scope; did you mean 'abs'?
  155 |   ans[m - 1] = n * (n - 1) / 2;
      |   ^~~
      |   abs
a.cc:157:18: error: 'a' was not declared in this scope
  157 |     if( uf.same( a[i], b[i] ) ){
      |                  ^
a.cc:157:24: error: 'b' was not declared in this scope
  157 |     if( uf.same( a[i], b[i] ) ){
      |                        ^