Efficient way to map ids

Question

I have two text files,

File 1 with data like

User game count

A Rugby 2
A Football 2
B Volleyball 1
C TT 2
...

File 2

Answer 1

Your File2 should have no records duplicated, such as no two football index records.

awk 'FNR==NR{a[$2]=$1;next}$0=$0 FS a[$2]' file2 file1