C - Water the Trees

https://codeforces.com/contest/1661/submission/153204750

Codeforces/1661/C/C.cpp

@@ -0,0 +1,52 @@
+#include <iostream>
+#include <limits>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 3e5 + 5;
+
+int t, n;
+long long max, sum, x, a[N], b[N], ans;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> t;
+
+    while (t--) {
+        ans = std::numeric_limits<long long>::max();
+        max = 0;
+
+        cin >> n;
+        for (int i = 1; i <= n; i++) {
+            cin >> a[i];
+            max = std::max(max, a[i]);
+        }
+
+        for (int _ = 1; _ <= 2; _++, max++) {
+            sum = x = 0;
+
+            for (int i = 1; i <= n; i++) {
+                b[i] = max - a[i];
+            }
+
+            for (int i = 1; i <= n; i++) {
+                sum += b[i] / 2 * 2;
+                x += b[i] % 2;
+            }
+
+            if (x * 2 > sum) {
+                ans = std::min(ans, x * 2 - 1);
+            } else {
+                sum -= x * 2;
+                ans = std::min(ans, x * 2 + sum / 3 * 2 + sum % 3);
+            }
+        }
+
+        cout << ans << endl;
+    }
+
+    return 0;
+}