Submission #6516950

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Source Code Expand

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

#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()
#define spa << " " <<
#define test cout<<"test"<<endl;
#define fi first
#define se second
typedef long long ll;
typedef long double ld;
const ll MOD = 1e9+7;
//const ll MOD = 998244353;
const ll INF = 1e18;
using P = pair<ll, ll>;
void chmin(ll &a,ll b){if(a>b)a=b;}
void chmax(ll &a,ll b){if(a<b)a=b;}
void pmod(ll &a,ll b){a=(a+b)%MOD;}
void pmod(ll &a,ll b,ll c){a=(b+c)%MOD;}
void qmod(ll &a,ll b){a=(a*b)%MOD;}
void qmod(ll &a,ll b,ll c){a=(b*c)%MOD;}
ll median(ll a,ll b, ll c){return a+b+c-max({a,b,c})-min({a,b,c});}
void ans1(bool x){if(x) cout<<"Yes"<<endl;else cout<<"No"<<endl;}
void ans2(bool x){if(x) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
void ans3(bool x){if(x) cout<<"Yay!"<<endl;else cout<<":("<<endl;}
void ans(bool x,ll y,ll z){if(x)cout<<y<<endl;else cout<<z<<endl;}
void ans(bool x,string y,string z){if(x)cout<<y<<endl;else cout<<z<<endl;}   
void debug(vector<vector<ll>>v,ll h,ll w){for(ll i=0;i<h;i++)
{cout<<v[i][0];for(ll j=1;j<w;j++)cout spa v[i][j];cout<<endl;}};
void debug(vector<string>v,ll h,ll w){for(ll i=0;i<h;i++)
{for(ll j=0;j<w;j++)cout<<v[i][j];cout<<endl;}};
void debug(vector<ll>v,ll n){cout<<v[0];
for(ll i=1;i<n;i++)cout spa v[i];cout<<endl;};
ll gcd(ll x,ll y){ll r;while((r=x%y)!=0){x=y;y=r;}return y;}
//m.emplace(x,0).fi->second++;

template< typename G >
struct DoublingLowestCommonAncestor {
  const ll LOG;
  vector< ll > dep;
  const G &g;
  vector< vector< ll > > table;

  DoublingLowestCommonAncestor(const G &g) : g(g), dep(g.size()), LOG(32 - __builtin_clz(g.size())) {
    table.assign(LOG, vector< ll >(g.size(), -1));
  }

  void dfs(ll idx, ll par, ll d) {
    table[0][idx] = par;
    dep[idx] = d;
    for(auto &to : g[idx]) {
      if(to != par) dfs(to, idx, d + 1);
    }
  }

  void build() {
    dfs(0, -1, 0);
    for(ll k = 0; k + 1 < LOG; k++) {
      for(ll i = 0; i < table[k].size(); i++) {
        if(table[k][i] == -1) table[k + 1][i] = -1;
        else table[k + 1][i] = table[k][table[k][i]];
      }
    }
  }

  ll query(ll u, ll v) {
    if(dep[u] > dep[v]) swap(u, v);
    for(ll i = LOG - 1; i >= 0; i--) {
      if(((dep[v] - dep[u]) >> i) & 1) v = table[i][v];
    }
    if(u == v) return u;
    for(ll i = LOG - 1; i >= 0; i--) {
      if(table[i][u] != table[i][v]) {
        u = table[i][u];
        v = table[i][v];
      }
    }
    return table[0][u];
  }
};



int main(){
  ll i,j,o;
  ll res=0,res1=INF,res2=-INF,buf=0;
  bool judge = true;
  ll n;cin>>n;
  vector<vector<ll>>listg(n);
  for(i=0;i<n-1;i++){
    ll p,q;cin>>p>>q;
    listg[p-1].push_back(q-1);
    listg[q-1].push_back(p-1);
  }
  DoublingLowestCommonAncestor<
  vector<vector<ll>>>tree(listg);
  tree.build();
  ll q;cin>>q;
  vector<ll>a(q),b(q);
  for(i=0;i<q;i++)cin>>a[i]>>b[i];
  for(i=0;i<q;i++){
    a[i]--;b[i]--;
    ll len=tree.dep[a[i]]+tree.dep[b[i]];
    len-=tree.dep[tree.query(a[i],b[i])]*2;
    cout<<len+1<<endl;
  }

  return 0;
}

Submission Info

Judge Result