'commit'

GESP/Level6/202503T2_Prepare.cpp

@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+using namespace std;
+typedef long long LL;
+const int N = 4e5 + 10;
+
+int n;
+LL a[N], s[N];
+LL ans = -1e18;
+
+int main() {
+  cin >> n;
+  for (int i = 1; i <= n; i++) {
+    cin >> a[i];
+    a[n + i] = a[i];
+  }
+
+  for (int i = 1; i <= 2 * n; i++)
+    s[i] = s[i - 1] + a[i];
+
+  // 对于每个位置i，枚举它前面n个位置，找最小前缀和
+  for (int i = 1; i <= 2 * n; i++) {
+    LL minPrefix = s[i - 1]; // 初始化为i-1位置的前缀和
+    for (int j = max(0, i - n); j <= i - 2; j++)
+      minPrefix = min(minPrefix, s[j]);
+    ans = max(ans, s[i] - minPrefix);
+  }
+
+  printf("%lld\n", ans);
+  return 0;
+}