Submission #18940724

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
typedef pair<int, int> PII;
typedef pair<LL,LL> PLL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef vector<bool> VB;
typedef vector<VB> VVB;
typedef vector<double> VD;
typedef vector<VD> VVD;
typedef vector<string> VS;
typedef vector<VS> VVS;
typedef vector<char> VC;
typedef vector<VC> VVC;
typedef vector<PII> VPII;
typedef vector<PLL> VPLL;
template<typename T>
using prque = priority_queue<T,vector<T>>;
template<typename T>
using prquer = priority_queue<T,vector<T>,greater<T>>;
#define umap unordered_map
#define uset unordered_set
#define umset unordered_multiset

#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EB emplace_back
#define EF emplace_front
#define PB push_back
#define PF push_front
#define POB pop_back
#define POF pop_front
#define MP make_pair
#define MT make_tuple
#define SZ(a) (int)((a).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define SORTR(c) sort((c).rbegin(), (c).rend())
#define REVERSE(c) reverse((c).begin(),(c).end())
#define LB lower_bound
#define UB upper_bound
#define NEXP(a) next_permutation((a).begin(),(a).end())
#define FI first
#define SE second

#define FOR(i,a,b) for(auto i = decltype(b){a}; i<(b); i++)
#define REP(i,n) FOR(i,0,n)
#define FORR(i,a,b) for(auto i=decltype(b){b-1}; i>=(a); i--)
#define REPR(i,n) FORR(i,0,n)
#define CFOR(i,a,b) for(auto i = decltype(b){a}; i<=(b); i++)
#define CREP(i,n) CFOR(i,0,n)
#define SREP(i,n) CFOR(i,1,n)
#define CFORR(i,a,b) for(auto i=decltype(b){b}; i>=(a); i--)
#define CREPR(i,n) CFORR(i,0,n)
#define SREPR(i,n) CFORR(i,1,n)
#define BFOR(bit,a,b) for(LL bit=(a); bit<(1ll<<(b)); bit++)
#define BREP(bit,n) BFOR(bit,0,n)
#define EACH(ptr,c) for(auto ptr=(c).begin(); ptr!=(c).end(); )
#define EACHR(ptr,c) for(auto ptr=(c).rbegin(); ptr!=(c).rend(); )

constexpr double EPS = 1e-10;
constexpr double PI  = 3.141592653589793238462643383279;
constexpr int INF = numeric_limits<int>::max()/2;
constexpr LL LINF = numeric_limits<LL>::max()/3;
constexpr int RINF = numeric_limits<int>::min()/2;
constexpr LL RLINF = numeric_limits<LL>::min()/3;
constexpr LL MOD = 1e9+7;
constexpr LL MODD = 998244353;
constexpr int MAX = 510000;

template<class T> inline T sqr(T x) { return x*x; }
inline bool Eq(double a, double b) { return fabs(b - a) < EPS; }
template<class T> inline T CEIL(T x, T y) { return (x+y-1)/y; }
inline int PCnt(uint64_t x) { return __builtin_popcountll(x); }

inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
inline LL toLL(string s) {LL v; istringstream sin(s);sin>>v;return v;}
inline double toDouble(string s) {double v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toStr(T x) {ostringstream sout;sout<<x;return sout.str();}

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

template<typename T>
T Vsum(vector<T> &v){return reduce(v.begin(),v.end()); }
template<typename T>
T Vgcd(vector<T> &v){return reduce(v.begin(),v.end(),T(0),[](auto&&a,auto&&b){return gcd(a,b);}); }
template<typename T>
T Vlcm(vector<T> &v){return reduce(v.begin(),v.end(),T(1),[](auto&&a,auto&&b){return lcm(a,b);}); }

template<typename T> T Vmax(vector<T> &v){return *max_element(v.begin(),v.end()); }
template<typename T> T Vmin(vector<T> &v){return *min_element(v.begin(),v.end()); }
template<typename T> void Vadd(vector<T> &v, T a){for(auto&& x : v) x += a; }

template<typename T>
vector<T> make_v(size_t a,T b){return vector<T>(a,b);}
template<typename... Ts>
auto make_v(size_t a,Ts... ts){return vector<decltype(make_v(ts...))>(a,make_v(ts...)); }

const vector<int> dx = {1,0,-1,0,1,1,-1,-1};
const vector<int> dy = {0,1,0,-1,1,-1,1,-1};

#define debug(x) cerr << #x <<" : "<< x << endl;
bool cYN(bool fl=true){cout << (fl?"Yes":"No") << endl; return fl; }
bool CYN(bool fl=true){cout << (fl?"YES":"NO") << endl; return fl; }
void error(bool fl=true){cout << -1 << endl; if(fl){ exit(0);} }
template<class T> void COUT(T&& t){ cout << t << endl; }
template<class T,class... Ts>
void COUT(T&& t,Ts&&... ts){ cout << t << " "; COUT(forward<Ts>(ts)...); }

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second; return is;
}
template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 >& p) {
  os << p.first << " " << p.second; return os;
}
template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}
template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < SZ(v); i++) os << v[i] << (i + 1 != SZ(v) ? " " : "");
  return os;
}


struct PartiallyPersistentUF {
  VI par, siz, last;
  int now;
  vector<VPII> hist;
  
  PartiallyPersistentUF() {}
  PartiallyPersistentUF(int n): par(n,-1),siz(n,1),last(n,INF),now(0) {
    iota(ALL(par),0);
    hist.assign(n,VPII(1,{0,1}));
  }
  void init(int n){
    par.resize(n);
    iota(ALL(par),0);
    siz.assign(n,1);
    last.assign(n,INF);
    now = 0;
    hist.assign(n,VPII(1,{0,1}));
  }

  int find(int t,int x) {
    while(last.at(x)<=t) x = par.at(x);
    return x;
  }

  pair<bool,int> unite(int x, int y){
    x = find(now, x);
    y = find(now, y);
    now++;
    if(x == y) return {false,now-1};

    if(siz[x] < siz[y]){
      swap(x,y);
    }
    siz[x] += siz[y];
    par[y] = x;
    last[y] = now;
    hist.at(x).EB(now, siz[x]);
    return {true, now-1};
  }

  bool same(int t, int x, int y){
    return find(t, x) == find(t, y);
  }

  int size(int t, int x){
    x = find(t, x);
    return prev(partition_point(
      ALL(hist.at(x)),
      [t](PII &h){ return h.FI<=t;})
      )->SE;
  }
};


int main() {

  // cin.tie(0);
  // ios::sync_with_stdio(false);
  cout << fixed << setprecision(12);
  
  int N, M;
  cin >> N >> M;
  PartiallyPersistentUF uf(N);
  REP(i,M){
    int a, b; cin >> a >> b; a--; b--;
    uf.unite(a,b);
  }
  int Q; cin >> Q;
  while(Q--){
    int x, y; cin >> x >> y; x--; y--;

    auto isok = [&](int t){
      return uf.same(t, x, y);
    };
    
    int ok = M+1, ng = -1;
    while(abs(ok-ng) > 1){
      int wj = (ok + ng)/2;
      if(isok(wj)) ok = wj;
      else ng = wj;
    }

    int res = ok; if(res > M) res = -1;
    COUT(res);
  }

  return 0;
}
/*
制約は見ましたか？
実行時間制限は見ましたか？
サンプルは試しましたか？
cat in.txt | .\a.exe > out.txt
C++になっていますか？
//*/

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