Problem p02851 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
#define ll long long int
#define me BOSS
#define bug() cout << "AIkahne aise" << endl
#define PI acos(-1)
ll A[5000001], bin[5000001];
vector<ll> v;
map<int, int> myMap;
set<int> mySet;
vector<pair<ll, ll>> vp;
/* Precode Start Here *\


power of 2 less than or equal to N

ll largest_power(ll N)
{
    //changing all right side bits to 1.
    N = N (N>>1);
    N = N| (N>>2);
    N = N| (N>>4);
    N = N| (N>>8);


//as now the number is 2 * x-1, where x is required answer, so adding 1 and
dividing it by 2. return (N+1)>>1;

}


     Sieve
void sieve()
{
    for(ll i=3; i<=2000; i+=2)
    {
        for(ll j=i*i; j<=4000000; j+=i)
            A[j]=1;
    }
    v.push_back(2);
    for(ll i=3; i<=4000000; i+=2)
        if(A[i]==0)
            v.push_back(i);
}

     Power Function Modulo P

ll modPow(ll a, ll x, ll p) {
    //calculates a^x mod p in logarithmic time.
    long res = 1;
    while(x > 0) {
        if( x % 2 != 0) {
            res = (res * a) % p;
        }
        a = (a * a) % p;
        x /= 2;
    }
    return res;
}


   factorial

ll fact(ll n)
{
    ll ans=1;
    for(ll i=1;i<=n;i++)
    {
        ans=(ans*i)%mod;
    }
    return ans;
}
     Calculating nCr using Fermats law Theorem

ll modInverse(ll a, ll p) {
    //calculates the modular multiplicative of a mod m.
    //(assuming p is prime).
    return modPow(a, p-2, p);
}


ll modBinomial(ll n, ll k, ll p) {
// calculates C(n,k) mod p (assuming p is prime).

    ll numerator = 1; // n * (n-1) * ... * (n-k+1)
    for (ll i=0; i<k; i++) {
        numerator = (numerator * (n-i) ) % p;
    }

    ll denominator = 1; // k!
    for (ll i=1; i<=k; i++) {
        denominator = (denominator * i) % p;
    }

    // numerator / denominator mod p.
    return ( numerator* modInverse(denominator,p) ) % p;
}
     num of divisor and euler totient

ll phi[1000001],mark[1000001],divi[1000001];;
void divisorPhi(ll n)
{
    for(int i=1;i<=n;i++)
        phi[i]=i;
    for(int i=2;i<=n;i++)
    {
        if(!mark[i])
        {
            for(int j=i;j<=n;j+=i)
            {
                mark[j]=1;
                phi[j]*=(1-1/(double)i);
            }
        }
    }
    for(ll i=1;i<=n;i++)
    {
        for(ll j=i;j<=n;j+=i)
            divi[j]++;
    }
}




/* Precode Ends */
ll sum[100001];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll n, k, ans = 0, a;
  cin >> n >> k;
  for (int i = 1; i <= n; i++) {
    cin >> A[i];
    sum[i] = (A[i] + sum[i - 1]) % k;
  }
  for (int i = 1; i <= n; i++) {
    sum[i] = (sum[i] - i) % k;
    sum[i] += k;
    sum[i] %= k;
    // cout<<sum[i]<<" ";
  }
  // myMap[0]=1;
  for (int i = 0; i <= n; i++) {
    ans += myMap[sum[i]];
    // cout<<ans<<" "<<myMap[sum[i]]<<" "<<sum[i]<<endl;
    myMap[sum[i]]++;
    if (i >= k - 1) {
      myMap[sum[i - k + 1]]--;
    }
  }
  cout << ans << endl;
  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
#define ll long long int
#define me BOSS
#define bug() cout << "AIkahne aise" << endl
#define PI acos(-1)
ll A[5000001], bin[5000001];
vector<ll> v;
map<int, int> myMap;
set<int> mySet;
vector<pair<ll, ll>> vp;
/* Precode Start Here *\


power of 2 less than or equal to N

ll largest_power(ll N)
{
    //changing all right side bits to 1.
    N = N (N>>1);
    N = N| (N>>2);
    N = N| (N>>4);
    N = N| (N>>8);


//as now the number is 2 * x-1, where x is required answer, so adding 1 and
dividing it by 2. return (N+1)>>1;

}


     Sieve
void sieve()
{
    for(ll i=3; i<=2000; i+=2)
    {
        for(ll j=i*i; j<=4000000; j+=i)
            A[j]=1;
    }
    v.push_back(2);
    for(ll i=3; i<=4000000; i+=2)
        if(A[i]==0)
            v.push_back(i);
}

     Power Function Modulo P

ll modPow(ll a, ll x, ll p) {
    //calculates a^x mod p in logarithmic time.
    long res = 1;
    while(x > 0) {
        if( x % 2 != 0) {
            res = (res * a) % p;
        }
        a = (a * a) % p;
        x /= 2;
    }
    return res;
}


   factorial

ll fact(ll n)
{
    ll ans=1;
    for(ll i=1;i<=n;i++)
    {
        ans=(ans*i)%mod;
    }
    return ans;
}
     Calculating nCr using Fermats law Theorem

ll modInverse(ll a, ll p) {
    //calculates the modular multiplicative of a mod m.
    //(assuming p is prime).
    return modPow(a, p-2, p);
}


ll modBinomial(ll n, ll k, ll p) {
// calculates C(n,k) mod p (assuming p is prime).

    ll numerator = 1; // n * (n-1) * ... * (n-k+1)
    for (ll i=0; i<k; i++) {
        numerator = (numerator * (n-i) ) % p;
    }

    ll denominator = 1; // k!
    for (ll i=1; i<=k; i++) {
        denominator = (denominator * i) % p;
    }

    // numerator / denominator mod p.
    return ( numerator* modInverse(denominator,p) ) % p;
}
     num of divisor and euler totient

ll phi[1000001],mark[1000001],divi[1000001];;
void divisorPhi(ll n)
{
    for(int i=1;i<=n;i++)
        phi[i]=i;
    for(int i=2;i<=n;i++)
    {
        if(!mark[i])
        {
            for(int j=i;j<=n;j+=i)
            {
                mark[j]=1;
                phi[j]*=(1-1/(double)i);
            }
        }
    }
    for(ll i=1;i<=n;i++)
    {
        for(ll j=i;j<=n;j+=i)
            divi[j]++;
    }
}




/* Precode Ends */
ll sum[300001];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll n, k, ans = 0, a;
  cin >> n >> k;
  for (int i = 1; i <= n; i++) {
    cin >> A[i];
    sum[i] = (A[i] + sum[i - 1]) % k;
  }
  for (int i = 1; i <= n; i++) {
    sum[i] = (sum[i] - i) % k;
    sum[i] += k;
    sum[i] %= k;
    // cout<<sum[i]<<" ";
  }
  // myMap[0]=1;
  for (int i = 0; i <= n; i++) {
    ans += myMap[sum[i]];
    // cout<<ans<<" "<<myMap[sum[i]]<<" "<<sum[i]<<endl;
    myMap[sum[i]]++;
    if (i >= k - 1) {
      myMap[sum[i - k + 1]]--;
    }
  }
  cout << ans << endl;
  return 0;
}