2551.java

class Solution {
    public long putMarbles(int[] weights, int k) {
        int n = weights.length;
        int[] arr = new int[n - 1];
        for (int i = 0; i < n - 1; ++i) {
            arr[i] = weights[i] + weights[i + 1];
        }
        Arrays.sort(arr);
        long ans = 0;
        for (int i = 0; i < k - 1; ++i) {
            ans -= arr[i];
            ans += arr[n - 2 - i];
        }
        return ans;
    }
}