Add C++ solution of problem #2554

Author: Cuda-Chen

2554/solution.cpp

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    int maxCount(vector<int>& banned, int n, int maxSum) {
+        unordered_set<int> m(begin(banned), end(banned));
+        int ans = 0;
+        int tmp = 0;
+        for(int i = 1; i <= n; i++) {
+            if(m.count(i))
+                continue;
+
+            if(tmp + i > maxSum)
+                break;
+            tmp += i;
+            ans++;
+        }
+        return ans;
+    }
+};