#include <bits/stdc++.h>   using namespace std;   const long long N = 2e5 + 3, mod = 1e9 + 7, inf = 3e18 + 7;   long long tc, n, m, a, b, c, d, i, j, k;   long long A[N], odd[N], even[N];   string s[N];   vector<long long> vec;   int main() {     ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);     cin >> tc;     while (tc--) {       cin >> n;       long long sum = 0, ans = 0, mx;       for (i = 1; i <= n; i++) cin >> A[i], sum += (i % 2 ? A[i] : 0);       A[n + 1] = A[n];       for (i = 2; i <= n; i += 2) even[i] = even[i - 2] + A[i] - A[i - 1];       for (i = 2; i <= n; i += 2) odd[i] = odd[i - 2] + A[i] - A[i + 1];       if (n % 2) n--;       for (i = n, mx = even[n]; i > 0; i -= 2)         mx = max(mx, even[i]), ans = max(ans, mx - even[i - 2]);       for (i = n, mx = odd[n]; i > 0; i -= 2)         mx = max(mx, odd[i]), ans = max(ans, mx - odd[i - 2]);       cout << ans + sum << endl;     }   }   