Sliding Window Sum

Code

#include <stdio.h>

void sliding_window_sum(int arr[], int n, int k) {
    int i, first, last;
    int sum;

    for(i = 0; i < k; i++)
        sum += arr[i];
    
    for(i = 0; i < n - k; i++)
    {
        printf("%d ", sum);
        first = arr[i];
        last = arr[k + i];
        sum += last - first;
    }
    printf("%d ", sum);
}

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