A bit straightforward which passes all tests:

void printKMax(int arr[], int n, int k) { std::deque subArr; int shift = 0; for(int a=0;a < k; ++a) subArr.push_back(arr[a]); // Get actual max value (iterator) auto maxval = std::max_element(subArr.begin(), subArr.end(), [](int a, int b){return a < b;}); // Get max value position int pos = maxval - subArr.begin(); cout << *maxval << ' ';

while(shift + k < n){
    subArr.pop_front(); // Remove old value
    subArr.push_back(arr[shift + k]); // Add new value 
    pos--; // Move max value position back

    // If new value is greater than actual max
    if(subArr.back() > *maxval){
        pos = subArr.size() - 1;
        maxval = subArr.begin() + pos;
    }
    else if(pos < 0){ // If not and old value ran out of scope find new max value
        maxval = std::max_element(subArr.begin(), subArr.end(), [](int a, int b){return a < b;});
        pos = maxval - subArr.begin();
    }

    // Print new max value
    cout << *maxval << ' ';
    shift++;
}

cout << '\n';

}

include

using namespace std; void print(vector &arr, int k) { deque dq; int n = arr.size();

for (int i = 0; i < n; ++i) {
    if (!dq.empty() && dq.front() == i - k)
        dq.pop_front();
    while (!dq.empty() && arr[dq.back()] < arr[i])
        dq.pop_back();
    dq.push_back(i);
    if (i >= k - 1)
        cout << arr[dq.front()] << " ";
}
cout << '\n';

}

int main() { // freopen("input.inp", "r", stdin); // freopen("output.out", "w", stdout); int t; cin >> t; while (t--) { int n, k; cin >> n >> k; vector arr(n); for (int i = 0; i < n; ++i) cin >> arr[i]; print(arr, k); } return 0; }

//Write your code here.
deque<int> d(arr,arr+k); //sub array
auto max = max_element(d.begin(),d.end()); //get max of sub array
cout << *max <<" "; 

//get max if max is removed
if(*max  == d.front())
    max = max_element(d.begin()+1,d.end());

d.pop_front(); //remove front element     

for(int i=k;i<n;++i){
    d.push_back(arr[i]);
    //check max
    if(arr[i] >= *max) 
        max = d.end()-1;              

    cout << *max <<" ";
    //get max if max is removed
    if(max  == d.begin()){ 
        max = max_element(d.begin()+1,d.end());
    }  
    d.pop_front();      
}

include

include

using namespace std;

void printKMax(int arr[], int n, int k){ deque deq; int i=0; deque::iterator it; for (i = 0; i < k; ++i) { while (!deq.empty() && arr[i] >= arr[deq.back()]) { deq.pop_back(); } deq.push_back(i); } for (; i < n; ++i) { cout << arr[deq.front()] << " "; while (!deq.empty() && deq.front() <= i - k) { deq.pop_front(); } while (!deq.empty() && arr[i] >= arr[deq.back()]) { deq.pop_back(); } deq.push_back(i); } cout << arr[deq.front()] << endl; }

int main(){

int t;
cin >> t;
while(t--) {
    int n,k;
    cin >> n >> k;
    int i;
    int arr[n];
    for(i=0;i<n;i++)
        cin >> arr[i];
    printKMax(arr, n, k);
}
return 0;

}

this also exceeded the time limit

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <deque>
using namespace std;

vector<vector<int>> makesubarray(deque<int> dq, int k) {
    vector<vector<int>> V;
    for (int i = 0; i <= dq.size() - k; i++) { // Change to <= to ensure valid subarray
        vector<int> v;
        for (int j = 0; j < k; j++) {
            v.push_back(dq[i + j]);
        }
        V.push_back(v);
    }
    return V;
}

deque<int> findmax(vector<vector<int>> v) {
    deque<int> dq;
    for (auto &a : v) {
        int max = a[0]; // Initialize max with the first element of the subarray
        for (int i = 1; i < a.size(); i++) { // Start from the second element
            if (a[i] > max) {
                max = a[i]; // Update max if current element is greater
            }
        }
        dq.push_back(max);
    }
    return dq;
}

int main() {
    int t;
    cin >> t;
    for (int i = 0; i < t; i++) {
        int n, k;
        cin >> n >> k;

        deque<int> dq;
        for (int j = 0; j < n; j++) {
            int element;
            cin >> element;
            dq.push_back(element);
        }
        
        for (auto &i : findmax(makesubarray(dq, k))) {
            cout << i << " "; // Add space for better formatting
        }
        cout << endl;
    }
    return 0;
}

`