problems(cpp): add “2390. Removing Stars From a String”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/removing-stars-from-a-string.cpp

@@ -0,0 +1,20 @@
+#include <string>
+#include <vector>
+
+class Solution {
+public:
+    std::string removeStars(const std::string& s)
+    {
+        std::vector<char> without_stars;
+
+        for (auto c : s) {
+            if (c == '*') {
+                without_stars.pop_back();
+            } else {
+                without_stars.push_back(c);
+            }
+        }
+
+        return std::string { without_stars.begin(), without_stars.end() };
+    }
+};