Create greatest-sum-divisible-by-three.cpp

Author: kamyu104

C++/greatest-sum-divisible-by-three.cpp

@@ -0,0 +1,20 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int maxSumDivThree(vector<int>& nums) {
+        vector<int> dp(3);
+        for (const auto& num : nums) {
+            vector<int> new_dp(dp);
+            for (auto& x : dp) {
+                x += num;
+            }
+            for (const auto& i : dp) {
+                new_dp[i % 3] = max(new_dp[i % 3], i);
+            }
+            dp = move(new_dp);
+        }
+        return dp[0];
+    }
+};