// 求所有前缀和和后缀和中的最大值 // 没要求一次遍历 long 発(vector<int> a) { unsigned int n = a.size(); // >0 long maxSum = a[0], minSum = a[0], sum = a[0]; for (unsigned int i = 1; i < n; i++) { sum += a[i]; maxSum = max(maxSum, sum); if (i != n - 1) minSum = min(minSum, sum); } return max(maxSum, sum - minSu...