関連ワード:  unordered_map c++ vector    unordered_map c++ vector as key    c++ unordered_map vs vector    c++ unordered_map with vector as value    c++ unordered_map vs vector performance    c++ unordered_map vs vector of pairs    c++ unordered_map insert vector    convert unordered_map to vector c++    c++ initialize unordered_map with vector    define unordered_map c++