342E - Xenia and Tree - CodeForces Solution

#include <bits/stdc++.h>
#include <chrono> 
 
using namespace std;
using namespace std::chrono; 
 
// #pragma GCC target ("avx2")
// #pragma GCC optimization ("O3")
// #pragma GCC optimization ("unroll-loops")
// #pragma optimization_level 3
// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
 
#define f0r(a, b) for (long long a = 0; a < (b); ++a)
#define f1r(a, b, c) for (long long a = (b); a < (c); ++a)
#define f0rd(a, b) for (long long a = (b); a >= 0; --a)
#define f1rd(a, b, c) for (long long a = (b); a >= (c); --a)
#define ms(arr, v) memset(arr, v, sizeof(arr))
#define pb push_back
#define send {ios_base::sync_with_stdio(false);}
#define help {cin.tie(NULL); cout.tie(NULL);}
#define fix(prec) {cout << setprecision(prec) << fixed;}
#define mp make_pair
#define f first
#define s second
#define all(v) v.begin(), v.end()
#define getunique(v) {sort(all(v)); v.erase(unique(all(v)), v.end());}
#define readgraph(list, edges) for (int i = 0; i < edges; i++) {int a, b; cin >> a >> b; a--; b--; list[a].pb(b); list[b].pb(a);}
#define ai(a, n) for (int ele = 0; ele < n; ele++) cin >> a[ele];
#define ain(a, lb, rb) for (int ele = lb; ele <= rb; ele++) cin >> a[ele];
#define ao(a, n) {for (int ele = 0; ele < (n); ele++) { if (ele) cout << " "; cout << a[ele]; } cout << '\n';}
#define aout(a, lb, rb) {for (int ele = (lb); ele <= (rb); ele++) { if (ele > (lb)) cout << " "; cout << a[ele]; } cout << '\n';}
#define vsz(x) ((long long) x.size())
typedef long long ll;
typedef long double lld;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
 
template<typename A> ostream& operator<<(ostream &cout, vector<A> const &v);
template<typename A, typename B> ostream& operator<<(ostream &cout, pair<A, B> const &p) { return cout << "(" << p.f << ", " << p.s << ")"; }
template<typename A> ostream& operator<<(ostream &cout, vector<A> const &v) {
	cout << "["; for(int i = 0; i < v.size(); i++) {if (i) cout << ", "; cout << v[i];} return cout << "]";
}
template<typename A, typename B> istream& operator>>(istream& cin, pair<A, B> &p) {
	cin >> p.first;
	return cin >> p.second;
}
 
mt19937 rng(steady_clock::now().time_since_epoch().count());
// mt19937 rng(61378913);
/* usage - just do rng() */
 
void usaco(string filename) {
  // #pragma message("be careful, freopen may be wrong")
	freopen((filename + ".in").c_str(), "r", stdin);
	freopen((filename + ".out").c_str(), "w", stdout);
}
 
const lld pi = 3.14159265358979323846;
// const ll mod = 1000000007;
// const ll mod = 998244353;
// ll mod;

struct lca_lift {
  const int lg = 24;
  int n;
  vector<int> depth;
  vector<vector<int> > edges;
  vector<vector<int> > lift;
  
  void init(int sz) {
    n = sz;
    depth = vector<int>(n);
    edges = vector<vector<int> >(n, vector<int>());
    lift = vector<vector<int> >(n, vector<int>(lg, -1));
  }

  void edge(int a, int b) {
    edges[a].push_back(b);
    edges[b].push_back(a);
  }

  void attach(int node_to_attach, int node_to_attach_to) {
    int a = node_to_attach, b = node_to_attach_to;
    edge(a, b);

    lift[a][0] = b;

    for (int i = 1; i < lg; i++) {
      if (lift[a][i - 1] == -1) lift[a][i] = -1;
      else lift[a][i] = lift[lift[a][i - 1]][i - 1];
    }

    depth[a] = depth[b] + 1;
  }

  void init_lift(int v = 0) {
    depth[v] = 0;
    dfs(v, -1);
  }

  void dfs(int v, int par) {
    lift[v][0] = par;

    for (int i = 1; i < lg; i++) {
      if (lift[v][i - 1] == -1) lift[v][i] = -1;
      else lift[v][i] = lift[lift[v][i - 1]][i - 1];
    }

    for (int x: edges[v]) {
      if (x != par) {
        depth[x] = depth[v] + 1;
        dfs(x, v);
      }
    }
  }

  int get(int v, int k) {
    for (int i = lg - 1; i >= 0; i--) {
	  if (v == -1) return v;
      if ((1 << i) <= k) {
        v = lift[v][i];
        k -= (1 << i);
      }
    }
    return v;
  }

  int get_lca(int a, int b) {
    if (depth[a] < depth[b]) swap(a, b);
    int d = depth[a] - depth[b];
    int v = get(a, d);
    if (v == b) {
      return v;
    } else {
      for (int i = lg - 1; i >= 0; i--) {
        if (lift[v][i] != lift[b][i]) {
          v = lift[v][i];
          b = lift[b][i];
        }
      }
      return lift[b][0];
    }
  }
  
  int get_dist(int a, int b) {
	  int v = get_lca(a, b);
	  return depth[a] + depth[b] - 2 * depth[v];
  }
};

struct centroid {
  vector<vector<int> > edges;
  vector<bool> vis;
  vector<int> par;
  vector<int> sz;
  int n;

  void init(int s) {
    n = s;
    edges = vector<vector<int> >(n, vector<int>());
    vis = vector<bool>(n, 0);
    par = vector<int>(n);
    sz = vector<int>(n);
  }

  void edge(int a, int b) {
    edges[a].pb(b);
    edges[b].pb(a);
  }

  int find_size(int v, int p = -1) {
    if (vis[v]) return 0;
    sz[v] = 1;

    for (int x: edges[v]) {
      if (x != p) {
        sz[v] += find_size(x, v);
      }
    }

    return sz[v];
  }

  int find_centroid(int v, int p, int n) {
    for (int x: edges[v]) {
      if (x != p) {
        if (!vis[x] && sz[x] > n / 2) {
          return find_centroid(x, v, n);
        }
      }
    }

    return v;
  }

  void init_centroid(int v = 0, int p = -1) {
    find_size(v);

    int c = find_centroid(v, -1, sz[v]);
    vis[c] = true;
    par[c] = p;

    for (int x: edges[c]) {
      if (!vis[x]) {
        init_centroid(x, c);
      }
    }
  }
};

ll n, m, k, q, l, r, x, y, z;
ll a[1000005];
ll b[1000005];
ll c[1000005];
string s, t;
ll ans = 0;

lca_lift lca;
centroid ct;
int best[100005];

void update(int v) {
	best[v] = 0;
	
	int u = v;
	while (ct.par[u] != -1) {
		u = ct.par[u];
		best[u] = min(best[u], lca.get_dist(u, v));
	}
}

int query(int v) {
	int ans = best[v];
	
	int u = v;
	while (ct.par[u] != -1) {
		u = ct.par[u];
		ans = min(ans, best[u] + lca.get_dist(u, v));
	}
	return ans;
}

void solve(int tc = 0) {
	cin >> n >> q;
	
	lca.init(n);
	ct.init(n);
	
	f0r(i, n) best[i] = 2e5;
	
	f0r(i, n - 1) {
		cin >> x >> y;
		--x; --y;
		lca.edge(x, y);
		ct.edge(x, y);
	}
	
	lca.init_lift();
	ct.init_centroid();
	
	update(0); // include this b/c node 1 is initially red
	
	f0r(i, q) {
		int t; cin >> t >> x;
		--x;
		
		if (t == 1) update(x);
		else cout << query(x) << '\n';
	}
}

int main() {
	#ifdef galen_colin_local
		auto begin = std::chrono::high_resolution_clock::now();
	#endif
	
	send help

	#ifndef galen_colin_local
		// usaco("cowland");
	#endif
	
	// usaco("cowland");

	int tc = 1;
	// cin >> tc;
	for (int t = 0; t < tc; t++) solve(t);
	
	#ifdef galen_colin_local
		auto end = std::chrono::high_resolution_clock::now();
		cout << setprecision(4) << fixed;
		// cout << "Execution time: " << std::chrono::duration_cast<std::chrono::duration<double>>(end - begin).count() << " seconds" << endl;
	#endif
}