Largest Sum Subarray of Size at least K
- we are using kadane to store the
maximum sum at every index.
- now comes the sliding window.
- after storing the sum of
[0 -> k].
- now @every step
- resize the sliding window.
- also check for the maximum subarray outside the sliding window since
at least k.
Implementation
```cpp
using ll = long long int;
ll maxSumWithK(ll arr[], ll n, ll k) {
using ll = long long int;
vector max_sum(n, 0);
max_sum[0] = arr[0];
ll curr_max = arr[0];
for (int i = 1; i < n; i++) {
curr_max = max(arr[i], curr_max + arr[i]);
max_sum[i] = curr_max;
}
ll sum = 0;
for (int i = 0; i < k; i++) {
sum += arr[i];
}
ll ans = sum;
for (int i = k; i < n; i++) {
sum += arr[i] - arr[i - k];
ans = max({ans, sum + max_sum[i - k], sum});
}
return ans;
}
```
</details>