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I'm reading the chapter Radix Search of the book Algorithms (Robert Sedgwick).

I've made a simple implementation and something isn't behaving as expected.

In program 15.5 you can see that we start with an empty tree where the head is a null node. In figure 15.12 you can see that the null node is always the leftmost node. This is also described in the text:

We use the convention that the leftmost link (the one correspond- ing to a key that is all 0 bits) does not point to any internal node

program 15.7 is the implementation of Patricia-trie insertion.

If you look at the code, there's never a chance for the head reference to change, let's say, to A as depicted in figure 15.12.

Is this a bug?

sleekster
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1 Answers1

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In Program 15.5 they state:

The root of the trie is at head.l (the link head.r is unused).

head.l does get assigned.

greybeard
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