Inderect references aka value of a value in awk

Question

I'm searching for a way to solve this problem in awk. Input:

X 1
Y 2
Z 3
X 4
Y 5

The output should look like this:

X 5
Y 7
Z 3

I see two problems here: the first one is the indirect reference in awk. Is it even possible?
It would work this way: if $$1 (X) exists add $2 else declare $$1 (X) then add $2
Even if I would figure out how to do it I would still need to know the name of all the declared variables i.e. X,Y,Z.

I'm guessing there is a simpler way to handle this task but I can't figure it out...

Answer 1

In awk array are associative, so the following works:

awk '{ vect[$1] += $2 }; 
 END { for (item in vect) print item, vect[item] }' input-file