2021/round2/valet_parking_ch2.cpp

#include <algorithm>
#include <iostream>
#include <iterator>
#include <set>
#include <vector>
using namespace std;

const int LIM = 2000005;

template<class T>
class segment_tree {
  static T join_values(const T &a, const T &b) {
    return min(a, b);
  }

  static T join_value_with_delta(const T &v, const T &d, int len) {
    return v + d;
  }

  static T join_deltas(const T &d1, const T &d2) {
    return d1 + d2;
  }

  int len;
  vector<T> value, delta;
  vector<bool> pending;

  void build(int i, int lo, int hi, const T &v) {
    if (lo == hi) {
      value[i] = v;
      return;
    }
    int mid = lo + (hi - lo)/2;
    build(i*2 + 1, lo, mid, v);
    build(i*2 + 2, mid + 1, hi, v);
    value[i] = join_values(value[i*2 + 1], value[i*2 + 2]);
  }

  void push_delta(int i, int lo, int hi) {
    if (pending[i]) {
      value[i] = join_value_with_delta(value[i], delta[i], hi - lo + 1);
      if (lo != hi) {
        int l = 2*i + 1, r = 2*i + 2;
        delta[l] = pending[l] ? join_deltas(delta[l], delta[i]) : delta[i];
        delta[r] = pending[r] ? join_deltas(delta[r], delta[i]) : delta[i];
        pending[l] = pending[r] = true;
      }
      pending[i] = false;
    }
  }

  T query(int i, int lo, int hi, int tgt_lo, int tgt_hi) {
    push_delta(i, lo, hi);
    if (lo == tgt_lo && hi == tgt_hi) {
      return value[i];
    }
    int mid = lo + (hi - lo)/2;
    if (tgt_lo <= mid && mid < tgt_hi) {
      return join_values(
                query(i*2 + 1, lo, mid, tgt_lo, min(tgt_hi, mid)),
                query(i*2 + 2, mid + 1, hi, max(tgt_lo, mid + 1), tgt_hi));
    }
    if (tgt_lo <= mid) {
      return query(i*2 + 1, lo, mid, tgt_lo, min(tgt_hi, mid));
    }
    return query(i*2 + 2, mid + 1, hi, max(tgt_lo, mid + 1), tgt_hi);
  }

  void update(int i, int lo, int hi, int tgt_lo, int tgt_hi, const T &d) {
    push_delta(i, lo, hi);
    if (hi < tgt_lo || lo > tgt_hi) {
      return;
    }
    if (tgt_lo <= lo && hi <= tgt_hi) {
      delta[i] = d;
      pending[i] = true;
      push_delta(i, lo, hi);
      return;
    }
    update(2*i + 1, lo, (lo + hi)/2, tgt_lo, tgt_hi, d);
    update(2*i + 2, (lo + hi)/2 + 1, hi, tgt_lo, tgt_hi, d);
    value[i] = join_values(value[2*i + 1], value[2*i + 2]);
  }

 public:
  segment_tree(int n, const T &v = T())
      : len(n), value(4*len), delta(4*len), pending(4*len, false) {
    build(0, 0, len - 1, v);
  }

  int size() const { return len; }
  T at(int i) { return query(i, i); }
  T query(int lo, int hi) { return query(0, 0, len - 1, lo, hi); }
  void update(int i, const T &d) { update(0, 0, len - 1, i, i, d); }
  void update(int lo, int hi, const T &d) { update(0, 0, len - 1, lo, hi, d); }
};

int R, C, K, S;
string G[LIM];
set<int> B[LIM];
set<int>::iterator I1[LIM], I2[LIM];

void add_car(segment_tree<int> &st, int r, int c) {
  // Shrink valid range.
  int i1 = *I1[c], i2 = *I2[c];
  B[c].insert(r);
  if (r > i1) {
    I1[c]++;
    st.update(i1 + 1, *I1[c] - 1, 1);
  }
  if (r < i2) {
    I2[c]--;
    st.update(*I2[c] + 1, i2 - 1, 1);
  }
  // Update added car index if in valid range.
  if (*I1[c] <= r && r <= *I2[c]) {
    st.update(r, r, 1);
  }
}

void remove_car(segment_tree<int> &st, int r, int c) {
  // Grow valid range.
  int i1 = *I1[c], i2 = *I2[c];
  if (r >= i1) {
    I1[c]--;
    st.update(*I1[c] + 1, i1 - 1, -1);
  }
  if (r <= i2) {
    I2[c]++;
    st.update(i2 + 1, *I2[c] - 1, -1);
  }
  B[c].erase(r);
  // Update removed car index if in valid range.
  if (*I1[c] <= r && r <= *I2[c]) {
    st.update(r, r, -1);
  }
}

long long solve() {
  for (int i = 0; i < LIM; i++) {
    B[i].clear();
    G[i].clear();
  }
  cin >> R >> C >> K >> S;
  for (int j = 0; j < C; j++) {
    // R - K + 1 cars before the beginning.
    for (int i = R - K; i >= 0; i--) {
      B[j].insert(-1 - i);
    }
    I1[j] = B[j].begin();
    // K cars after the end.
    for (int i = K - 1; i >= 0; i--) {
      B[j].insert(R + 2 + i);
    }
    I2[j] = prev(B[j].end());
  }
  segment_tree<int> st(R + 2);
  for (int i = 0; i <= R + 1; i++) {
    st.update(i, i, abs(i - K));
    if (1 <= i && i <= R) {
      cin >> G[i];
      for (int j = 0; j < C; j++) {
        if (G[i][j] == 'X') {
          add_car(st, i, j);
        }
      }
    }
  }
  long long ans = 0;
  while (S--) {
    int i, j;
    cin >> i >> j;
    j--;
    if (G[i][j] == 'X') {
      G[i][j] = '.';
      remove_car(st, i, j);
    } else {
      G[i][j] = 'X';
      add_car(st, i, j);
    }
    ans += st.query(0, R + 1);
  }
  return ans;
}

int main() {
  int T;
  cin >> T;
  for (int t = 1; t <= T; t++) {
    cout << "Case #" << t << ": " << solve() << endl;
  }
  return 0;
}