Update sort-an-array.cpp

Author: kamyu104

C++/sort-an-array.cpp

@@ -25,7 +25,7 @@ class Solution {
             }
             tmp.emplace_back((*nums)[i]);
         }
-        copy(tmp.begin(), tmp.end(), nums->begin() + start);
+        copy(tmp.cbegin(), tmp.cend(), nums->begin() + start);
     }
 };