Problem p03074 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;

#define MEM(a, b) memset(a, (b), sizeof(a))
#define FORN(i, a, n) for (int i = a; i < n; i++)
#define FRON(i, a, n) for (int i = a; i > n; i--)
#define FOR(i, n) for (int i = 0; i < n; i++)
#define FRO(i, a) for (int i = a; i > -1; i--)
#define mp make_pair
#define pb push_back
#define INF 1000000010
#define MOD 1000000007 // 998244353
#define PI 3.141592653589793238462643383279502884197169399375105820974945
#define FASTIO ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<ll> vll;
typedef pair<int, int> pii;
typedef vector<string> vs;
typedef vector<vi> vii;

// debugging output in cerr
#define n_l '\n'
#define debug(...)                                                             \
  cerr << "[" << #__VA_ARGS__ << "]: ";                                        \
  cerr << to_string(__VA_ARGS__) << endl
template <typename T, size_t N> int SIZE(const T (&t)[N]) { return N; }
template <typename T> int SIZE(const T &t) { return t.size(); }
string to_string(const string s, int x1 = 0, int x2 = 1e9) {
  return '"' + ((x1 < s.size()) ? s.substr(x1, x2 - x1 + 1) : "") + '"';
}
string to_string(const char *s) { return to_string((string)s); }
string to_string(const bool b) { return (b ? "true" : "false"); }
string to_string(const char c) { return string({c}); }
template <size_t N>
string to_string(const bitset<N> &b, int x1 = 0, int x2 = 1e9) {
  string t = "";
  for (int __iii__ = min(x1, SIZE(b)), __jjj__ = min(x2, SIZE(b) - 1);
       __iii__ <= __jjj__; ++__iii__) {
    t += b[__iii__] + '0';
  }
  return '"' + t + '"';
}
template <typename A, typename... C>
string to_string(const A(&v), int x1 = 0, int x2 = 1e9, C... coords);
int l_v_l_v_l = 0, t_a_b_s = 0;
template <typename A, typename B> string to_string(const pair<A, B> &p) {
  l_v_l_v_l++;
  string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
  l_v_l_v_l--;
  return res;
}
template <typename A, typename... C>
string to_string(const A(&v), int x1, int x2, C... coords) {
  int rnk = rank<A>::value;
  string tab(t_a_b_s, ' ');
  string res = "";
  bool first = true;
  if (l_v_l_v_l == 0)
    res += n_l;
  res += tab + "[";
  x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v));
  auto l = begin(v);
  advance(l, x1);
  auto r = l;
  advance(r, (x2 - x1) + (x2 < SIZE(v)));
  for (auto e = l; e != r; e = next(e)) {
    if (!first) {
      res += ", ";
    }
    first = false;
    l_v_l_v_l++;
    if (e != l) {
      if (rnk > 1) {
        res += n_l;
        t_a_b_s = l_v_l_v_l;
      };
    } else {
      t_a_b_s = 0;
    }
    res += to_string(*e, coords...);
    l_v_l_v_l--;
  }
  res += "]";
  if (l_v_l_v_l == 0)
    res += n_l;
  return res;
}
void debugm() { ; }
template <typename Heads, typename... Tails> void debugm(Heads H, Tails... T) {
  cerr << to_string(H) << " | ";
  debugm(T...);
}
#define debugm(...)                                                            \
  cerr << "[" << #__VA_ARGS__ << "]: ";                                        \
  debugm(__VA_ARGS__);                                                         \
  cerr << endl

double round(double num, int dec) {
  return std::round(num * pow(10, dec)) / pow(10, dec);
}
vector<string> split(string s, char delim) {
  replace(s.begin(), s.end(), delim, ' ');
  stringstream ss(s);
  string buf;
  vector<string> v;
  while (ss >> buf)
    v.push_back(buf);
  return v;
}
template <typename T, int size> int siz(T (&)[size]) { return size; }
long long POW(long long base, long long exp) {
  long long res = 1;
  while (exp > 0) {
    if (exp % 2 == 1) {
      res = (res * base) % MOD;
    }
    exp = exp >> 1;
    base = (base * base) % MOD;
  }
  return res;
}

int main() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1) {
    cout << 1;
    return 0;
  }
  vi zero;
  vi one;
  bool end = false;
  if (s[0] == '0' && s[n - 1] == '0') {
    one.pb(0);
    end = true;
  } else if (s[0] == '0' && s[n - 1] == '1') {
    one.pb(0);
  } else if (s[0] == '1' && s[n - 1] == '0') {
    end = true;
  }
  int count = 1;
  for (int i = 1; i < n; i++) {
    if (s[i] != s[i - 1]) {
      if (s[i - 1] == '0') {
        zero.pb(count);
      } else {
        one.pb(count);
      }
      count = 0;
    }
    count++;
  }
  if (s[n - 1] == '0') {
    zero.pb(count);
  } else {
    one.pb(count);
  }
  if (end) {
    one.pb(0);
  }

  debug(zero);
  debug(one);
  int temp = 0;
  // zero sliding window
  for (int i = 0; i < k; i++) {
    temp += zero[i];
  }
  // ones sliding window
  for (int i = 0; i < k + 1; i++) {
    temp += one[i];
  }
  int ans = 0;
  ans = max(temp, ans);
  // continue window
  for (int i = k; i < zero.size(); i++) {
    temp -= zero[i - k];
    temp += zero[i];
    temp -= one[i - k];
    temp += one[i + 1];
    ans = max(temp, ans);
    debug(temp);
  }
  cout << ans;
}

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

#define MEM(a, b) memset(a, (b), sizeof(a))
#define FORN(i, a, n) for (int i = a; i < n; i++)
#define FRON(i, a, n) for (int i = a; i > n; i--)
#define FOR(i, n) for (int i = 0; i < n; i++)
#define FRO(i, a) for (int i = a; i > -1; i--)
#define mp make_pair
#define pb push_back
#define INF 1000000010
#define MOD 1000000007 // 998244353
#define PI 3.141592653589793238462643383279502884197169399375105820974945
#define FASTIO ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<ll> vll;
typedef pair<int, int> pii;
typedef vector<string> vs;
typedef vector<vi> vii;

// debugging output in cerr
#define n_l '\n'
#define debug(...)                                                             \
  cerr << "[" << #__VA_ARGS__ << "]: ";                                        \
  cerr << to_string(__VA_ARGS__) << endl
template <typename T, size_t N> int SIZE(const T (&t)[N]) { return N; }
template <typename T> int SIZE(const T &t) { return t.size(); }
string to_string(const string s, int x1 = 0, int x2 = 1e9) {
  return '"' + ((x1 < s.size()) ? s.substr(x1, x2 - x1 + 1) : "") + '"';
}
string to_string(const char *s) { return to_string((string)s); }
string to_string(const bool b) { return (b ? "true" : "false"); }
string to_string(const char c) { return string({c}); }
template <size_t N>
string to_string(const bitset<N> &b, int x1 = 0, int x2 = 1e9) {
  string t = "";
  for (int __iii__ = min(x1, SIZE(b)), __jjj__ = min(x2, SIZE(b) - 1);
       __iii__ <= __jjj__; ++__iii__) {
    t += b[__iii__] + '0';
  }
  return '"' + t + '"';
}
template <typename A, typename... C>
string to_string(const A(&v), int x1 = 0, int x2 = 1e9, C... coords);
int l_v_l_v_l = 0, t_a_b_s = 0;
template <typename A, typename B> string to_string(const pair<A, B> &p) {
  l_v_l_v_l++;
  string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
  l_v_l_v_l--;
  return res;
}
template <typename A, typename... C>
string to_string(const A(&v), int x1, int x2, C... coords) {
  int rnk = rank<A>::value;
  string tab(t_a_b_s, ' ');
  string res = "";
  bool first = true;
  if (l_v_l_v_l == 0)
    res += n_l;
  res += tab + "[";
  x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v));
  auto l = begin(v);
  advance(l, x1);
  auto r = l;
  advance(r, (x2 - x1) + (x2 < SIZE(v)));
  for (auto e = l; e != r; e = next(e)) {
    if (!first) {
      res += ", ";
    }
    first = false;
    l_v_l_v_l++;
    if (e != l) {
      if (rnk > 1) {
        res += n_l;
        t_a_b_s = l_v_l_v_l;
      };
    } else {
      t_a_b_s = 0;
    }
    res += to_string(*e, coords...);
    l_v_l_v_l--;
  }
  res += "]";
  if (l_v_l_v_l == 0)
    res += n_l;
  return res;
}
void debugm() { ; }
template <typename Heads, typename... Tails> void debugm(Heads H, Tails... T) {
  cerr << to_string(H) << " | ";
  debugm(T...);
}
#define debugm(...)                                                            \
  cerr << "[" << #__VA_ARGS__ << "]: ";                                        \
  debugm(__VA_ARGS__);                                                         \
  cerr << endl

double round(double num, int dec) {
  return std::round(num * pow(10, dec)) / pow(10, dec);
}
vector<string> split(string s, char delim) {
  replace(s.begin(), s.end(), delim, ' ');
  stringstream ss(s);
  string buf;
  vector<string> v;
  while (ss >> buf)
    v.push_back(buf);
  return v;
}
template <typename T, int size> int siz(T (&)[size]) { return size; }
long long POW(long long base, long long exp) {
  long long res = 1;
  while (exp > 0) {
    if (exp % 2 == 1) {
      res = (res * base) % MOD;
    }
    exp = exp >> 1;
    base = (base * base) % MOD;
  }
  return res;
}

int main() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1) {
    cout << 1;
    return 0;
  }
  vi zero;
  vi one;
  bool end = false;
  if (s[0] == '0' && s[n - 1] == '0') {
    one.pb(0);
    end = true;
  } else if (s[0] == '0' && s[n - 1] == '1') {
    one.pb(0);
  } else if (s[0] == '1' && s[n - 1] == '0') {
    end = true;
  }
  int count = 1;
  for (int i = 1; i < n; i++) {
    if (s[i] != s[i - 1]) {
      if (s[i - 1] == '0') {
        zero.pb(count);
      } else {
        one.pb(count);
      }
      count = 0;
    }
    count++;
  }
  if (s[n - 1] == '0') {
    zero.pb(count);
  } else {
    one.pb(count);
  }
  if (end) {
    one.pb(0);
  }

  debug(zero);
  debug(one);
  int len = zero.size();
  k = min(k, len);
  int temp = 0;
  // zero sliding window
  for (int i = 0; i < k; i++) {
    temp += zero[i];
  }
  // ones sliding window
  for (int i = 0; i < k + 1; i++) {
    temp += one[i];
  }
  int ans = 0;
  ans = max(temp, ans);
  // continue window
  for (int i = k; i < zero.size(); i++) {
    temp -= zero[i - k];
    temp += zero[i];
    temp -= one[i - k];
    temp += one[i + 1];
    ans = max(temp, ans);
    debug(temp);
  }
  cout << ans;
}