Problem p03074 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
const ll MOD = 1000000007;
const ll nmax = 8;
const ll INF = 1e9;
bool graph[nmax][nmax];
vector<vector<ll>> dist = vector<vector<ll>>(nmax, vector<ll>(nmax, INF));
void warshall_floyd(ll n) {
  for (size_t i = 0; i < n; i++) {
    for (size_t j = 0; j < n; j++) {
      for (size_t k = 0; k < n; k++) {
        dist[j][k] = min(dist[j][k], dist[j][i] + dist[i][k]);
      }
    }
  }
}

class UnionFind {
public:
  vector<ll> Parent;

  UnionFind(ll N) { Parent = vector<ll>(N, -1); }
  ll find(ll A) {
    if (Parent[A] < 0)
      return A;
    return Parent[A] = find(Parent[A]);
  }

  ll size(ll A) { return -Parent[find(A)]; }

  bool Union(ll A, ll B) {
    A = find(A);
    B = find(B);
    if (A == B) {
      return false;
    }
    if (size(A) < size(B))
      swap(A, B);

    Parent[A] += Parent[B];
    Parent[B] = A;

    return true;
  }
};

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
  ll g = gcd(a, b);
  return a / g * b;
}

ll mulMod(ll a, ll b) { return (((a % MOD) * (b % MOD)) % MOD); }

ll powMod(ll a, ll p) {
  if (p == 0) {
    return 1;
  } else if (p % 2 == 0) {
    ll half = powMod(a, p / 2);
    return mulMod(half, half);
  } else {
    return mulMod(powMod(a, p - 1), a);
  }
}

void solve(long long N, long long K, string S) {
  vector<ll> map;

  bool isZero;
  bool firstZero;
  if (S[0] == '0') {
    isZero = true;
    firstZero = true;
    map.push_back(0);
  } else {
    isZero = false;
    firstZero = false;
  }
  int cnt = 0;

  for (int i = 0; i < N; i++) {
    if (isZero) {
      if (S[i] == '1') {
        map.push_back(cnt);
        cnt = 0;
        isZero = false;
      }
    } else {
      if (S[i] == '0') {
        map.push_back(cnt);
        cnt = 0;
        isZero = true;
      }
    }
    cnt++;
  }
  if (cnt != 0)
    map.push_back(cnt);

  if (map.size() % 2 == 0)
    map.push_back(0);

  int limit = 2 * K + 1;
  int ans = 0;
  for (int i = 0; i < map.size(); i += 2) {
    int tmp = 0;
    int left = i;
    int right = min(i + limit, (int)map.size());
    for (int j = i; j < i + limit; j++) {
      tmp += map[j];
    }
    ans = max(tmp, ans);
  }
  cout << ans << endl;
}

int main() {
  long long N;
  scanf("%lld", &N);
  long long K;
  scanf("%lld", &K);
  string S;
  cin >> S;
  solve(N, K, S);
  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
const ll MOD = 1000000007;
const ll nmax = 8;
const ll INF = 1e9;
bool graph[nmax][nmax];
vector<vector<ll>> dist = vector<vector<ll>>(nmax, vector<ll>(nmax, INF));
void warshall_floyd(ll n) {
  for (size_t i = 0; i < n; i++) {
    for (size_t j = 0; j < n; j++) {
      for (size_t k = 0; k < n; k++) {
        dist[j][k] = min(dist[j][k], dist[j][i] + dist[i][k]);
      }
    }
  }
}

class UnionFind {
public:
  vector<ll> Parent;

  UnionFind(ll N) { Parent = vector<ll>(N, -1); }
  ll find(ll A) {
    if (Parent[A] < 0)
      return A;
    return Parent[A] = find(Parent[A]);
  }

  ll size(ll A) { return -Parent[find(A)]; }

  bool Union(ll A, ll B) {
    A = find(A);
    B = find(B);
    if (A == B) {
      return false;
    }
    if (size(A) < size(B))
      swap(A, B);

    Parent[A] += Parent[B];
    Parent[B] = A;

    return true;
  }
};

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
  ll g = gcd(a, b);
  return a / g * b;
}

ll mulMod(ll a, ll b) { return (((a % MOD) * (b % MOD)) % MOD); }

ll powMod(ll a, ll p) {
  if (p == 0) {
    return 1;
  } else if (p % 2 == 0) {
    ll half = powMod(a, p / 2);
    return mulMod(half, half);
  } else {
    return mulMod(powMod(a, p - 1), a);
  }
}

void solve(long long N, long long K, string S) {
  vector<ll> map;

  bool isZero;
  bool firstZero;
  if (S[0] == '0') {
    isZero = true;
    firstZero = true;
    map.push_back(0);
  } else {
    isZero = false;
    firstZero = false;
  }
  int cnt = 0;

  for (int i = 0; i < N; i++) {
    if (isZero) {
      if (S[i] == '1') {
        map.push_back(cnt);
        cnt = 0;
        isZero = false;
      }
    } else {
      if (S[i] == '0') {
        map.push_back(cnt);
        cnt = 0;
        isZero = true;
      }
    }
    cnt++;
  }
  if (cnt != 0)
    map.push_back(cnt);

  if (map.size() % 2 == 0)
    map.push_back(0);

  int limit = 2 * K + 1;
  int ans = 0;
  for (int i = 0; i < map.size(); i += 2) {
    int tmp = 0;
    int left = i;
    int right = min(i + limit, (int)map.size());
    for (int j = i; j < right; j++) {
      tmp += map[j];
    }
    ans = max(tmp, ans);
  }
  cout << ans << endl;
}

int main() {
  long long N;
  scanf("%lld", &N);
  long long K;
  scanf("%lld", &K);
  string S;
  cin >> S;
  solve(N, K, S);
  return 0;
}