13. Standard Library swap algoritm

• 
      #include <iostream>
      #include <algorithm>
  
      int main()
      {
          int dummy[] = { 1, 2, 3, 4, 5 };
  
          // Swap elements:
          std::swap( dummy[ 0 ], dummy[ 4 ] );
  
          // Display elements of dummy array:
          std::cout
              << dummy[ 0 ]
              << '\t'
              << dummy[ 4 ]
              << '\n'
              ;
  
          return 0;
      }
  
      /* Program output:
      5       1
      */