Map Notes for Fall 2023

• Note: Kattis claims that it is compiling with -std=gnu++17 so don't use any features beyond that.
• The map is a dynamic array index by an arbitrary value.
  • This is called a dictionary in other langagues
  • This is called a hash table in data structures.
  • This is good if we want to keep track of something like the number of times each person voted.
  • We will index by person name.
• We need
  • #include <map>
  • map<indexType, valueType> id
• And probably
  • #include <algorithm>
• mapVar[indexType] = valueType
• if (mapVar.find(indexType) == end(mapVar)) {
• .size() does what you want.
• You can use this loop to visit all nodes in the map

  • for (auto x : map) {
       //x.first is the index 
       //x.second is the data
       cout << "map[ " << x.first <<"] = " << x.second;
    }
         

• See shopping.cpp.