Language: C++

#include <bits/stdc++.h>
#include <iomanip>
#include <math.h>
//#include <unistd.h>
//#include <stdio.h>
#define rep(i,x) for(ll i = 0;i<x;i++)
#define all(a) (a).begin(),(a).end()
using ll = long long;
using ld = long double;
using namespace std;
using dou = double;
const ll inf = 2147483647;
const ll INF = 1LL << 60;
const ld pi = 3.14159265358;
const ll mod = 1000000007;
typedef pair<ll,ll> P;
using graph = vector<vector<ll>>;
template<class T> inline bool chmax(T& a, T b){if(a < b){a = b; return true;}return false;}
template<class T> inline bool chmin(T& a, T b){if(a > b){a = b; return true;}return false;}
ll gcd(ll a,ll b){
    if(a < b)swap(a,b);
    if(a % b == 0)return b;
    else return gcd(b,a%b);
}
//素数判定O(sqrt(N))
bool isp(ll n){
    bool res = true;
    if(n == 1)return false;
    else{
        for(ll i = 2;i * i <= n;i++){
            if(n % i == 0){
                res = false;
                break;
            }
        }
        return res;
    }
}

ll fac[510000], finv[510000], inv[510000];

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (ll i = 2; i < 510000; i++){
        fac[i] = fac[i - 1] * i % mod;
        inv[i] = mod - inv[mod%i] * (mod / i) % mod;
        finv[i] = finv[i - 1] * inv[i] % mod;
    }
}

// 二項係数計算
ll nCk(ll n, ll k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % mod) % mod;
}
//nのm乗をMODで割ったあまりO(logN)
ll modpow(ll n,ll m,ll MOD){
    ll res = 1;
    while(m){
        if(m & 1)res = (res * n) % MOD;
        m >>= 1;
        n *= n;
        n %= MOD;
    }
    return res;
}

//printf("%.10f\n", N);
/*  vector<ll> vec = {1,2,5,6,8,9,10};
    cout << binary_search(all(vec),5) << endl; -> true*/
/*
    vector<ll> vec = {1,2,5,6,8,9,10};
    auto n = upper_bound(all(vec),4);
    cout << *n << endl; -> 5*/

//    cout << fixed << setprecision(15);
const ll MAX = 100000;
ll par[MAX];
ll ran[MAX];
ll size[MAX];
void init(ll n){
    rep(i,n){
        size[i] = 1;
        par[i] = i;
        ran[i] = 0;
    }
}
ll find(ll x){
    if(x == par[x])return x;
    else return par[x] = find(par[x]);
}
void unite(ll x,ll y){
    x = find(x);
    y = find(y);
    if(x == y)return;
    if(ran[x] < ran[y]){
        size[y] += size[x];
        par[x] = y;
    }
    else{
        size[x] += size[y];
        par[y] = x;
        if(ran[x] == ran[y])ran[x]++;
    }
}
bool same(ll x,ll y){
    return find(x) == find(y);
}
ll get_size(ll x){
    return size[find(x)];
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll N,M;
    cin >> N >> M;
    COMinit();
    vector<ll> fr(M),to(M);
    rep(i,M){
        cin >> fr[i] >> to[i];
        fr[i]--;to[i]--;
    }
    init(N);
    vector<ll> ans(M);
    ans[M - 1] = N * (N - 1) / 2;
    //rep(i,M)cout << ans[i] << "\n";
    for(ll i = M - 1;i > 0;i--){
        /*rep(j,N){
            cout << size(j) << " ";
        }
        cout << "\n";*/
        if(same(fr[i],to[i])){
            ans[i - 1] = ans[i];
        }
        else{
            ans[i - 1] = ans[i] - get_size(fr[i]) * get_size(to[i]);
            unite(fr[i],to[i]);
        }
    }
    rep(i,M)cout << ans[i] << "\n";
    //rep(i,N)cout << size(i) << "\n";
}

Compiler output:
a.cc: In function 'void init(ll)':
a.cc:87:9: error: reference to 'size' is ambiguous
   87 |         size[i] = 1;
      |         ^~~~
In file included from /usr/include/c++/14/string:53,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:84:4: note:                 'll size [100000]'
   84 | ll size[MAX];
      |    ^~~~
a.cc: In function 'void unite(ll, ll)':
a.cc:101:9: error: reference to 'size' is ambiguous
  101 |         size[y] += size[x];
      |         ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:84:4: note:                 'll size [100000]'
   84 | ll size[MAX];
      |    ^~~~
a.cc:101:20: error: reference to 'size' is ambiguous
  101 |         size[y] += size[x];
      |                    ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:84:4: note:                 'll size [100000]'
   84 | ll size[MAX];
      |    ^~~~
a.cc:105:9: error: reference to 'size' is ambiguous
  105 |         size[x] += size[y];
      |         ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:84:4: note:                 'll size [100000]'
   84 | ll size[MAX];
      |    ^~~~
a.cc:105:20: error: reference to 'size' is ambiguous
  105 |         size[x] += size[y];
      |                    ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:84:4: note:                 'll size [100000]'
   84 | ll size[MAX];
      |    ^~~~
a.cc: In function 'll get_size(ll)':
a.cc:114:12: error: reference to 'size' is ambiguous
  114 |     return size[find(x)];
      |            ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:84:4: note:                 'll size [100000]'
   84 | ll size[MAX];
      |    ^~~~