description: You are given a sequence a of length n consisting of 0s and 1s.
  
  You can perform the following operation on this sequence: 
  
    * Pick an index i from 1 to n-2 (inclusive). 
    * Change all of a_{i}, a_{i+1}, a_{i+2} to a_{i} ⊕ a_{i+1} ⊕ a_{i+2} simultaneously, where ⊕ denotes the [bitwise XOR operation](https://en.wikipedia.org/wiki/Bitwise_operation#XOR)
  
  Find a sequence of at most n operations that changes all elements of a to 0s or report that it's impossible.
  
  We can prove that if there exists a sequence of operations of any length that changes all elements of a to 0s, then there is also such a sequence of length not greater than n.
  
  Input
  
  Each test contains multiple test cases. The first line contains the number of test cases t (1 ≤ t ≤ 10^4).
  
  The first line of each test case contains a single integer n (3 ≤ n ≤ 2⋅10^5) — the length of a.
  
  The second line of each test case contains n integers a_1, a_2, …, a_n (a_i = 0 or a_i = 1) — elements of a.
  
  It is guaranteed that the sum of n over all test cases does not exceed 2⋅10^5.
  
  Output
  
  For each test case, do the following: 
  
    * if there is no way of making all the elements of a equal to 0 after performing the above operation some number of times, print "NO". 
    * otherwise, in the first line print "YES", in the second line print k (0 ≤ k ≤ n) — the number of operations that you want to perform on a, and in the third line print a sequence b_1, b_2, ..., b_k (1 ≤ b_i ≤ n - 2) — the indices on which the operation should be applied. 
  
  
  
  If there are multiple solutions, you may print any.
  
  Example
  
  Input
  
  
  3
  3
  0 0 0
  5
  1 1 1 1 0
  4
  1 0 0 1
  
  
  Output
  
  
  YES
  0
  YES
  2
  3 1
  NO
  
  Note
  
  In the first example, the sequence contains only 0s so we don't need to change anything.
  
  In the second example, we can transform [1, 1, 1, 1, 0] to [1, 1, 0, 0, 0] and then to [0, 0, 0, 0, 0] by performing the operation on the third element of a and then on the first element of a.
  
  In the third example, no matter whether we first perform the operation on the first or on the second element of a we will get [1, 1, 1, 1], which cannot be transformed to [0, 0, 0, 0].
solution: #include <bits/stdc++.h>
  using namespace std;
  vector<int> solve_odd(vector<int> v, int offset) {
    int n = v.size();
    vector<int> ans;
    for (int i = 0; i < n - 2; i += 2) {
      v[i] = v[i + 1] = v[i + 2] = v[i] ^ v[i + 1] ^ v[i + 2];
      ans.push_back(i + offset);
    }
    for (int i = n - 3; i >= 0; i -= 2) ans.push_back(i + offset);
    return ans;
  }
  void solve() {
    int n;
    cin >> n;
    vector<int> v;
    int x = 0;
    for (int i = 0; i < n; i++) {
      int d;
      cin >> d;
      x ^= d;
      v.push_back(d);
    }
    if (x) {
      cout << "NO\n";
      return;
    }
    vector<int> ans;
    if (n % 2 == 1)
      ans = solve_odd(v, 1);
    else {
      int x = 0, ind = -1;
      for (int i = 0; i < n; i++) {
        x ^= v[i];
        if (!x && i % 2 == 0) {
          ind = i;
          break;
        }
      }
      if (ind == -1) {
        cout << "NO\n";
        return;
      }
      vector<int> l, r;
      for (int i = 0; i < n; i++)
        if (i <= ind)
          l.push_back(i);
        else
          r.push_back(i);
      ans = solve_odd(l, 1);
      auto oans = solve_odd(r, ind + 2);
      ans.insert(ans.end(), oans.begin(), oans.end());
    }
    cout << "YES\n";
    cout << ans.size() << "\n";
    for (auto i : ans) cout << i << " ";
    cout << "\n";
  }
  int main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);
    int t;
    cin >> t;
    while (t--) solve();
  }
  