Update k-concatenation-maximum-sum.cpp

Author: kamyu104

C++/k-concatenation-maximum-sum.cpp

@@ -6,18 +6,19 @@ class Solution {
     int kConcatenationMaxSum(vector<int>& arr, int k) {
         static const int MOD = 1e9 + 7;
         if (k == 1) {
-            return maxSubKArray(arr, 1) % MOD;
+            return max(maxSubKArray(arr, 1), 0) % MOD;
         }
-        return (maxSubKArray(arr, 2) +
+        return (max(maxSubKArray(arr, 2), 0) +
                 (k - 2) * max(accumulate(arr.cbegin(), arr.cend(), 0ll), 0ll)) % MOD;
     }
 
 private:
     int maxSubKArray(const vector<int>& nums, int k) {
-        int result = 0, curr = 0;
+        int result = numeric_limits<int>::min();
+        int curr = numeric_limits<int>::min();
         for (int i = 0; i < k; ++i) {
             for (const auto& x : nums) {
-                curr = max(curr + x, x);
+                curr = (curr == numeric_limits<int>::min()) ? x : max(curr + x, x);
                 result = max(result, curr);
             }
         }