Sliding Window Sum

O(n)

#include <stdio.h>

void sliding_window_sum(int arr[], int n, int k) {
    int sum = 0;
    // Calculate sum of first window
    for (int i = 0; i < k; i++) {
        sum += arr[i];
    }
    printf("%d ", sum);

    // Slide the window
    for (int i = k; i < n; i++) {
        sum += arr[i] - arr[i - k];
        printf("%d ", sum);
    }
    printf("\n");
}

int main() {
    int n, k, arr[100];
    scanf("%d %d", &n, &k);
    for (int i = 0; i < n; i++) scanf("%d", &arr[i]);

    sliding_window_sum(arr, n, k);
    return 0;
}

Solving Approach