求条 C

#include <bits/stdc++.h>
using namespace std;

const int N = 4e5 + 5;
int n, m;
long long a[N], b[N];

void solve() {
	cin >> n >> m;
	long long sum = 0, ans = 0;
	for (int i = 1; i <= n; i++) cin >> a[i];
	for (int i = 0; i < m * 2; i++) {
		b[i] = 0;
		for (int j = i; j <= n; j += m * 2) {
			b[i] += a[j];
		}
		if (i < m) sum += b[i];
	}
	ans = sum;
	for (int i = 0; i < m; i++) {
		sum = sum - b[i] + b[i + m];
		ans = min(ans, sum);
	}
	cout << ans << '\n';
}

int main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	int _; cin >> _;
	while (_--) solve();
	return 0;
}