What wrong in my code three cast case is failed

#1

#include
using namespace std;
#include
void window(deque g,int a[],int n,int k){
int max=0;
int f=0;;
for(int i=0;i<k;i++){
if(max<a[i]){
max=a[i];
f=i;
}}
for(int l=f;l<k;l++){
g.push_back(l); }

   for(int d=k;d<n;d++){
       cout<<a[g.front()]<<" ";
   while(!g.empty()&&a[d]>=a[g.back()]){
      g.pop_back();
   }
       while((!g.empty())&&(g.front()<=(d-k))){
           g.pop_front();
       }
       
       g.push_back(d);
        
   }
   cout<<a[g.front()];

}
int main()
{
int n;
cin>>n;
int a[n];
for(int i=0;i<n;i++){
cin>>a[i];
}
int k;
cin>>k;
deque g;
window(g,a,n,k);

return 0;

}

#2 
for (int i = 0; i < k; i++)
    {
        if (mx< a[i])
        {
            mx= a[i];
            f = i;
        }
    }
    for (int l = f; l < k; l++)
    {
        g.push_back(l);
    }

Your code is failing in these lines,
u have to mantain the dequeue in a fashion of decreasing order of valued index.
Try something like this for the first k elements:

for(int i = 0 ; i < k ; i++){
while((!q.empty()) and a[i] > a[q.front()])
q.pop_back();
q.push_back(i);
}

In case of further doubts do ask.

#3

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