init commit

contests/2contest/4.cpp

@@ -0,0 +1,28 @@
+#include <string>
+using namespace std;
+
+class BinaryNumber
+{
+    string str;
+public:
+    BinaryNumber(const string& s = "0") {
+        str = s;
+    }
+    operator string () const {
+        return str;
+    }
+    const BinaryNumber& operator++() {
+        std::string::iterator i = str.end() - 1;
+        while (*i == '1' && i != str.begin()) {
+            *i = '0';
+            --i;
+        }
+        if (i == str.begin()) {
+            str.insert(str.begin(), '1');
+        } else {
+            *i = '1';
+        }
+
+        return *this;
+    }
+};