#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,avx,mmx,tune=native")
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define ll long long
signed main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int t;
	cin >> t;
	while(t--){
		int n, s;
		cin >> n >> s;
		int a[n];
		for(int i = 0; i < n; i++){
			cin >> a[i];
		}
		ll sum = 0;
		for(int i = 1; i < n-1; i++){
			int x = a[i];
			int y = s * 2;
			sum += min(x, y) * a[i-1] + abs(x-y) * a[n-1];
		}
		cout << sum << endl;
 
	}
	return 0;
}

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

MTAKNSAwCjIgMCAxIDMgNAo1IDEKNSAzIDQgMyA1CjcgMgo3IDYgNSA0IDMgMiAxCjUgMQoxIDIgMyA0IDUKNSAyCjEgMiAzIDQgNQo0IDAKMCAxIDEgMQo1IDUKNCAzIDUgNiA0CjQgMQowIDIgMSAwCjMgOTk5OTkKMjAwMDAwIDIwMDAwMCAyMDAwMDAKNiA4MTM5Cjc5NzYgMTI5Nzg1IDEyOTg0IDc4NTYxIDE3MzY4NSAxNTQ4MAo=

10
5 0
2 0 1 3 4
5 1
5 3 4 3 5
7 2
7 6 5 4 3 2 1
5 1
1 2 3 4 5
5 2
1 2 3 4 5
4 0
0 1 1 1
5 5
4 3 5 6 4
4 1
0 2 1 0
3 99999
200000 200000 200000
6 8139
7976 129785 12984 78561 173685 15480