Best Way to Find the Array Contains a Given String - c++

Question

I have some arrays of strings and a function that gets a string and return the type of it (the array that the string belongs to)
How can I do it with the best speed?
string arr1[] = {"a", "b", "c"};
string arr2[] = {"d", "e", "f"};
string arr3[] = {"g", "h", "i"};
string arr4[] = {"j", "k", "l"};
...
string getFamily(string input)
{
if(arr1.contains(input)
return "TYPE_1";
...
}
Thanks

Answer 1

This is not elegant, but if you want fast, you can make a prepared unordered_map to do the search which would be useful if this function will be called 100s of times (wasteful if rarely called). Ideally, you can make this container in a class object rather than a global variable and the return type an integral value rather than a string. This would produce a search of O(1) with the cost being in the hashing of the key. But I do not know enough of your requirements.
If you would rather call once, then do as Joachim Pileborg suggested and do a series of std::find calls until you get a hit.
#include <iostream>
#include <unordered_map>
#include <string>
std::unordered_map< std::string, std::string > g_map;
std::string arr1[] = {"a", "b", "c"};
std::string arr2[] = {"d", "e", "f"};
std::string arr3[] = {"g", "h", "i"};
std::string arr4[] = {"j", "k", "l"};
const char * map_value( const std::string & input )
{
std::unordered_map< std::string, std::string >::iterator iter( g_map.find( input ) );
return iter == g_map.end() ? "NOT FOUND" : iter->second.c_str();
}
int main( int argc, char ** argv )
{
// Build the map;
for( int i = 0; i < sizeof( arr1 ) / sizeof( std::string ); ++i )
g_map[arr1[i]] = "TYPE_1";
for( int i = 0; i < sizeof( arr2 ) / sizeof( std::string ); ++i )
g_map[arr2[i]] = "TYPE_2";
for( int i = 0; i < sizeof( arr3 ) / sizeof( std::string ); ++i )
g_map[arr3[i]] = "TYPE_3";
for( int i = 0; i < sizeof( arr4 ) / sizeof( std::string ); ++i )
g_map[arr4[i]] = "TYPE_4";
std::string input;
std::cout << map_value( "b" ) << std::endl;
std::cout << map_value( "z" ) << std::endl;
std::cout << map_value( "eb" ) << std::endl;
std::cout << map_value( "j" ) << std::endl;
std::cout << map_value( "f" ) << std::endl;
return 0;
}
Output:
TYPE_1
NOT FOUND
NOT FOUND
TYPE_4
TYPE_2