##### λ Tony's Blog λ

## Raf’s Problem

Posted on March 11, 2008Raf – a colleague – gave me the following problem:

Given a String (x) containing only characters a-z, write a function (f) that returns a base 10 integer, which converts the String as if it were a base 26 numeral. Function f is bijective.

Here are some example runs:

```
x | f(x)
empty | 0
a | 1
b | 2
z | 26
aa | 27
az | 52
ba | 53
bz | 78
aaa | 703
aaz | 728
aza | 1353
```

Using your preferred programming language, implement function f.

My solution is in a comment on this page. What is yours?