Problem p02647 (C++)

Buggy submission (status: Time Limit Exceeded):
#include "bits/stdc++.h"
using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define LL long long

const int MAXSSTN = 200010;
class StarrySkyTree {
public:
  int size = 0;
  int depth = 0; // the depth of the tree
  int best = 0;  // the index of maximum element
  int start = 0; // the initial index of inputs
  long long dat_add[4 * MAXSSTN];
  long long dat[4 * MAXSSTN];

  StarrySkyTree(int n) {
    size = n;
    while ((1 << depth) < n)
      depth++;
    start = (1 << depth) - 1;
    for (int i = start; i < (1 << (depth + 1)); i++) {
      if (i < start + n)
        dat[i] = 0;
      else
        dat[i] = 1e15;
    }
    for (int i = start; i < start + n; i++) {
      int tmp = i;
      while (par(tmp) != -1) {
        dat[par(tmp)] = min(dat[tmp], dat[(tmp + 1) / 2 * 4 - 1 - tmp]);
        tmp = par(tmp);
      }
    }
    int i = 0;
    while (i < start)
      i = (dat[i] == dat[2 * i + 1]) ? 2 * i + 1 : 2 * i + 2;
    best = i - start;
  }
  long long max_element(int a, int b) {
    return max_element(a, b, 0, 0, (1 << depth));
  }
  void add(int s, int t, int x) { add(s, t, 0, 0, (1 << depth), x); }
  void add(int i, int x) { add(i, i + 1, 0, 0, (1 << depth), x); }

  int par(int i) {
    if (i == 0)
      return -1;
    return (i - 1) / 2;
  }

  void clear() {
    for (int i = start; i < (1 << (depth + 1)); i++) {
      if (i < start + size)
        dat[i] = 0;
      else
        dat[i] = 1e15;
    }
    for (int i = start; i < start + size; i++) {
      int tmp = i;
      while (par(tmp) != -1) {
        dat[par(tmp)] = min(dat[tmp], dat[(tmp + 1) / 2 * 4 - 1 - tmp]);
        tmp = par(tmp);
      }
    }
    int i = 0;
    while (i < start)
      i = (dat[i] == dat[2 * i + 1]) ? 2 * i + 1 : 2 * i + 2;
    best = i - start;

    REP(i, 4 * MAXSSTN) dat_add[i] = 0;
  }

  void update(int d, long long x) {
    int i = d + start;
    dat[i] = x;
    while (par(i) != -1) {
      dat[par(i)] = min(dat[i], dat[(i + 1) / 2 * 4 - 1 - i]);
      i = par(i);
    }
    i = 0;
    while (i < start) {
      i = (dat[i] == dat[2 * i + 1]) ? 2 * i + 1 : 2 * i + 2;
    }
    best = i - start;
  }
  void dump() {
    for (int i = 0; i < (1 << (depth + 1)); i++) {
      cerr << dat[i] << " ";
    }
    cerr << endl;
  }

private:
  long long max_element(int a, int b, int k, int l, int r) {
    if (b <= l || r <= a)
      return 1e15;
    if (a <= l && r <= b)
      return dat[k] + dat_add[k];

    long long vl = max_element(a, b, k * 2 + 1, l, (l + r) / 2);
    long long vr = max_element(a, b, k * 2 + 2, (l + r) / 2, r);
    return min(vl, vr) + dat_add[k];
  }
  void add(int a, int b, int k, int l, int r, long long x) {
    if (b <= l || r <= a)
      return;
    if (a <= l && r <= b) {
      dat_add[k] += x;
    } else {
      add(a, b, k * 2 + 1, l, (l + r) / 2, x);
      add(a, b, k * 2 + 2, (l + r) / 2, r, x);
      dat[k] = min(dat[k * 2 + 1] + dat_add[k * 2 + 1],
                   dat[k * 2 + 2] + dat_add[k * 2 + 2]);
    }
  }
};

int n, k;
int a[200000];

int main() {
  cin >> n >> k;
  REP(i, n) cin >> a[i];
  if (k >= 41) {
    REP(i, n) cout << n << " ";
    cout << endl;
    return 0;
  }

  StarrySkyTree sst(n);
  REP(i, k) {
    REP(j, n) sst.update(j, 0);
    REP(j, n) { sst.add(max(0, j - a[j]), min(n - 1, j + a[j]) + 1, 1); }
    REP(j, n) { a[j] = sst.max_element(j, j + 1); }
    sst.clear();
  }

  REP(i, n) cout << a[i] << " ";
  cout << endl;
  return 0;
}


Fixed submission:
#include "bits/stdc++.h"
using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define LL long long

const int MAXSSTN = 200010;
class StarrySkyTree {
public:
  int size = 0;
  int depth = 0; // the depth of the tree
  int best = 0;  // the index of maximum element
  int start = 0; // the initial index of inputs
  long long dat_add[4 * MAXSSTN];
  long long dat[4 * MAXSSTN];

  StarrySkyTree(int n) {
    size = n;
    while ((1 << depth) < n)
      depth++;
    start = (1 << depth) - 1;
    for (int i = start; i < (1 << (depth + 1)); i++) {
      if (i < start + n)
        dat[i] = 0;
      else
        dat[i] = 1e15;
    }
    for (int i = start; i < start + n; i++) {
      int tmp = i;
      while (par(tmp) != -1) {
        dat[par(tmp)] = min(dat[tmp], dat[(tmp + 1) / 2 * 4 - 1 - tmp]);
        tmp = par(tmp);
      }
    }
    int i = 0;
    while (i < start)
      i = (dat[i] == dat[2 * i + 1]) ? 2 * i + 1 : 2 * i + 2;
    best = i - start;
  }
  long long max_element(int a, int b) {
    return max_element(a, b, 0, 0, (1 << depth));
  }
  void add(int s, int t, int x) { add(s, t, 0, 0, (1 << depth), x); }
  void add(int i, int x) { add(i, i + 1, 0, 0, (1 << depth), x); }

  int par(int i) {
    if (i == 0)
      return -1;
    return (i - 1) / 2;
  }

  void clear() {
    for (int i = start; i < (1 << (depth + 1)); i++) {
      if (i < start + size)
        dat[i] = 0;
      else
        dat[i] = 1e15;
    }
    for (int i = start; i < start + size; i++) {
      int tmp = i;
      while (par(tmp) != -1) {
        dat[par(tmp)] = min(dat[tmp], dat[(tmp + 1) / 2 * 4 - 1 - tmp]);
        tmp = par(tmp);
      }
    }
    int i = 0;
    while (i < start)
      i = (dat[i] == dat[2 * i + 1]) ? 2 * i + 1 : 2 * i + 2;
    best = i - start;

    REP(i, 4 * MAXSSTN) dat_add[i] = 0;
  }

  void update(int d, long long x) {
    int i = d + start;
    dat[i] = x;
    while (par(i) != -1) {
      dat[par(i)] = min(dat[i], dat[(i + 1) / 2 * 4 - 1 - i]);
      i = par(i);
    }
    i = 0;
    while (i < start) {
      i = (dat[i] == dat[2 * i + 1]) ? 2 * i + 1 : 2 * i + 2;
    }
    best = i - start;
  }
  void dump() {
    for (int i = 0; i < (1 << (depth + 1)); i++) {
      cerr << dat[i] << " ";
    }
    cerr << endl;
  }

private:
  long long max_element(int a, int b, int k, int l, int r) {
    if (b <= l || r <= a)
      return 1e15;
    if (a <= l && r <= b)
      return dat[k] + dat_add[k];

    long long vl = max_element(a, b, k * 2 + 1, l, (l + r) / 2);
    long long vr = max_element(a, b, k * 2 + 2, (l + r) / 2, r);
    return min(vl, vr) + dat_add[k];
  }
  void add(int a, int b, int k, int l, int r, long long x) {
    if (b <= l || r <= a)
      return;
    if (a <= l && r <= b) {
      dat_add[k] += x;
    } else {
      add(a, b, k * 2 + 1, l, (l + r) / 2, x);
      add(a, b, k * 2 + 2, (l + r) / 2, r, x);
      dat[k] = min(dat[k * 2 + 1] + dat_add[k * 2 + 1],
                   dat[k * 2 + 2] + dat_add[k * 2 + 2]);
    }
  }
};

int n, k;
int a[200000];

int main() {
  cin >> n >> k;
  REP(i, n) cin >> a[i];
  if (k >= 41) {
    REP(i, n) cout << n << " ";
    cout << endl;
    return 0;
  }

  StarrySkyTree sst(n);
  REP(i, k) {
    REP(j, n) sst.update(j, 0);
    REP(j, n) { sst.add(max(0, j - a[j]), min(n - 1, j + a[j]) + 1, 1); }
    REP(j, n) {
      if (a[j] != n || !i)
        a[j] = sst.max_element(j, j + 1);
    }
    sst.clear();
  }

  REP(i, n) cout << a[i] << " ";
  cout << endl;
  return 0;
}