B - Xor of 3

https://codeforces.com/contest/1572/submission/173868979

Codeforces/1572/B/B.cpp

@@ -0,0 +1,68 @@
+#include <iostream>
+#include <algorithm>
+#include <functional>
+#include <numeric>
+#include <queue>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2e5 + 5;
+
+int t, n, a[N], s[N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> t;
+
+    while (t--) {
+        std::queue<int> q;
+
+        cin >> n;
+
+        for (int i = 1; i <= n; i++) {
+            cin >> a[i];
+        }
+
+        std::partial_sum(a + 1, a + 1 + n, s + 1, std::bit_xor<>());
+
+        auto process = [&](int l, int r) -> void {
+            for (int i = r - 2; i >= l; i -= 2) q.emplace(i);
+            for (int i = l; i < r; i += 2) q.emplace(i);
+        };
+
+        if (!s[n]) {
+            if (n % 2) {
+                process(1, n);
+            } else {
+                for (int i = 1; i <= n; i += 2) {
+                    if (!s[i]) {
+                        process(1, i);
+                        process(i + 1, n);
+                        break;
+                    }
+                }
+            }
+        }
+
+        if (!q.empty()) {
+            cout << "YES" << endl
+                 << q.size() << endl;
+
+            while (!q.empty()) {
+                cout << q.front() << ' ';
+                q.pop();
+            }
+
+            cout << endl;
+        } else {
+            cout << "NO" << endl;
+        }
+    }
+
+    return 0;
+}