QTree

Main.java

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.TreeMap;
import java.util.Map;
import java.io.InputStream;

/**
 * Built using CHelper plug-in Actual solution is at the top
 *
 * @author MaxHeap
 */
public class Main {

  public static void main(String[] args) {
    InputStream inputStream = System.in;
    OutputStream outputStream = System.out;
    InputReader in = new InputReader(inputStream);
    PrintWriter out = new PrintWriter(outputStream);
    QuTree solver = new QuTree();
    solver.solve(1, in, out);
    out.close();
  }

  static class QuTree {

    final int MAX_LOG = 17;
    final int INF = 1 << 30;
    List<Integer>[] tree;
    int[][] parent;
    int[] depth;
    boolean[] color;
    MultiSet<Integer>[] answer;
    int n;
    QTreeSolver solver;
    CentroidComposer<Integer> composer = (a, b) -> 0;
    CentroidTemplate<Integer> centroidTemplate;

    void dfs(int u, int p) {
      for (int v : tree[u]) {
        if (v != p) {
          parent[0][v] = u;
          depth[v] = depth[u] + 1;
          dfs(v, u);
        }
      }
    }

    void initialize() {
      answer = new MultiSet[n + 1];
      color = new boolean[n + 1];
      for (int i = 0; i <= n; i++) {
        answer[i] = new MultiSet<>();
        answer[i].add(INF);
      }
      parent = new int[MAX_LOG][n + 1];
      depth = new int[n + 1];
      depth[1] = 1;
      dfs(1, 0);
      for (int i = 1; i < MAX_LOG; i++) {
        for (int j = 1; j <= n; j++) {
          parent[i][j] = parent[i - 1][parent[i - 1][j]];
        }
      }
    }

    int lca(int u, int v) {
      if (depth[u] > depth[v]) {
        int tmp = u;
        u = v;
        v = tmp;
      }
      int diff = depth[v] - depth[u];
      for (int i = 0; i < MAX_LOG && diff > 0; i++) {
        if (Bits.isSet(diff, i)) {
          v = parent[i][v];
          Bits.unset(diff, i);
        }
      }
      if (u == v) {
        return v;
      }
      for (int i = MAX_LOG - 1; i >= 0; i--) {
        if (parent[i][u] != parent[i][v]) {
          u = parent[i][u];
          v = parent[i][v];
        }
      }
      return parent[0][u];
    }

    int distance(int u, int v) {
      return depth[u] + depth[v] - 2 * depth[lca(u, v)];
    }

    void updateWhite(int u) {
      color[u] = true;
      int cur = u;
      while (cur > 0) {
        answer[cur].add(distance(u, cur));
        cur = solver.parent[cur];
      }
    }

    void updateBlack(int u) {
      color[u] = false;
      int cur = u;
      while (cur > 0) {
        answer[cur].remove(distance(u, cur));
        cur = solver.parent[cur];
      }
    }

    int query(int u) {
      int ret = INF;
      int cur = u;
      while (cur > 0) {
        ret = Math.min(ret, answer[cur].firstKey() + distance(cur, u));
        cur = solver.parent[cur];
      }
      return ret;
    }

    public void solve(int testNumber, InputReader in, PrintWriter out) {
      n = in.nextInt();
      tree = GraphUtils.generateGraph(n + 1);
      for (int i = 0; i < n - 1; i++) {
        int u = in.nextInt();
        int v = in.nextInt();
        tree[u].add(v);
        tree[v].add(u);
      }
      initialize();

      solver = new QTreeSolver(n + 1);

      centroidTemplate = new CentroidTemplate<>(tree, n + 1, solver, composer);

      centroidTemplate.solve(1, 0);

//    out.println(Arrays.toString(solver.parent));
      int q = in.nextInt();
      while (q-- > 0) {
        int type = in.nextInt();
        int u = in.nextInt();
        if (type == 0) {
          if (color[u]) {
            updateBlack(u);
          } else {
            updateWhite(u);
          }
        } else {
          int ret = query(u);
          out.println(ret >= INF ? -1 : ret);
        }
      }
    }

    class QTreeSolver implements CentroidSolver<Integer> {

      public int[] parent;

      public QTreeSolver(int n) {
        parent = new int[n];
      }

      public Integer work(List<Integer>[] tree, int n, int centroid, int centroidParent,
          boolean[] removed, int[] subTreeSize) {
        parent[centroid] = centroidParent;
        return null;
      }

    }

  }

  static interface CentroidSolver<T> {

    T work(List<Integer>[] tree, int n, int centroid, int centroidParent, boolean[] removed,
        int[] subTreeSize);

  }

  static interface CentroidComposer<T> {

    T compose(T a, T b);

  }

  static final class Bits {

    private Bits() {
      throw new UnsupportedOperationException("cannot instantiate Bits class");
    }

    public static boolean isSet(int mask, int i) {
      return (mask & (1 << i)) > 0;
    }

    public static int unset(int mask, int k) {
      return (mask & ~(1 << k));
    }

  }

  static class InputReader {

    private InputStream stream;
    private byte[] buf = new byte[1 << 13];
    private int curChar;
    private int numChars;

    public InputReader(InputStream stream) {
      this.stream = stream;
    }

    public int read() {
      if (this.numChars == -1) {
        throw new UnknownError();
      } else {
        if (this.curChar >= this.numChars) {
          this.curChar = 0;

          try {
            this.numChars = this.stream.read(this.buf);
          } catch (IOException ex) {
            throw new InputMismatchException();
          }

          if (this.numChars <= 0) {
            return -1;
          }
        }

        return this.buf[this.curChar++];
      }
    }

    public int nextInt() {
      int c;
      for (c = this.read(); isSpaceChar(c); c = this.read()) {
      }

      byte sgn = 1;
      if (c == 45) {
        sgn = -1;
        c = this.read();
      }

      int res = 0;

      while (c >= 48 && c <= 57) {
        res *= 10;
        res += c - 48;
        c = this.read();
        if (isSpaceChar(c)) {
          return res * sgn;
        }
      }

      throw new InputMismatchException();
    }

    public static boolean isSpaceChar(int c) {
      return c == 32 || c == 10 || c == 13 || c == 9 || c == -1;
    }

  }

  static class GraphUtils {

    private GraphUtils() {
    }

    public static List<Integer>[] generateGraph(int n) {
      List<Integer>[] graph = new ArrayList[n];
      for (int i = 0; i < n; i++) {
        graph[i] = new ArrayList<>();
      }
      return graph;
    }

  }

  static class CentroidTemplate<T> {

    List<Integer>[] tree;
    boolean[] removed;
    int[] subTreeSize;
    int[] depth;
    int n;
    CentroidSolver<T> solver;
    CentroidComposer<T> composer;

    public CentroidTemplate(List<Integer>[] tree, int n, CentroidSolver<T> solver,
        CentroidComposer<T> composer) {
      this.solver = solver;
      this.n = n;
      this.tree = tree;
      removed = new boolean[n];
      subTreeSize = new int[n];
      depth = new int[n];
      this.composer = composer;
    }

    public T solve(int root, int parent) {
      computeSubtreeSize(root, parent);
      int centroid = findCentroid(root, parent, subTreeSize[root]);
      T result = solver.work(tree, n, centroid, parent,
          removed, subTreeSize);
      removed[centroid] = true;
      for (int u : tree[centroid]) {
        if (u == parent || removed[u]) {
          continue;
        }
        result = composer.compose(result, solve(u, centroid));
      }
      return result;
    }

    int findCentroid(int cur, int par, int comp) {
      for (int nxt : tree[cur]) {
        if (nxt == par || removed[nxt]) {
          continue;
        }
        if (subTreeSize[nxt] > comp / 2) {
          return findCentroid(nxt, cur, comp);
        }
      }
      return cur;
    }

    private void computeSubtreeSize(int u, int p) {
      subTreeSize[u] = 1;
      for (int nxt : tree[u]) {
        if (nxt == p || removed[nxt]) {
          continue;
        }
        computeSubtreeSize(nxt, u);
        subTreeSize[u] += subTreeSize[nxt];
      }
    }

  }

  static class MultiSet<E> {

    private TreeMap<E, Integer> map;

    public MultiSet() {
      map = new TreeMap<>();
    }

    public void add(E val) {
      map.put(val, map.getOrDefault(val, 0) + 1);
    }

    public void remove(E val) {
      Integer cur = map.get(val);
      if (cur == null) {
        return;
      }
      if (cur > 1) {
        map.put(val, cur - 1);
      } else {
        map.remove(val);
      }
    }

    public E firstKey() {
      return map.firstKey();
    }

  }
}