the getMax function in binary search tree may not work correctly #50

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claunia · 2026-01-29T15:01:56Z

claunia commented

2026-01-29 15:01:56 +00:00

Originally created by @bayegy on GitHub (Jul 12, 2020).

Hi there,
I am learning data structure. it's really helpful to find such a excellent project. Thanks for the excellent work.

However, I found this code may not work correctly.
08415b0f16/data_structures/binary_trees/binary_search_tree.c (L65)

let's say we have a tree like this
node *root = NULL;
root = insert(root, 100);
root = insert(root, 50);
root = insert(root, 25);
root = insert(root, 12);
root = insert(root, 35);
root = insert(root, 75);
root = insert(root, 58);
root = insert(root, 87);
root = insert(root, 150);
root = insert(root, 125);
root = insert(root, 175);
root = insert(root, 168);
root = insert(root, 180);

When I want to delete 50 from this tree, getMax function returns 25 for the max data of the left subtree of node 50, which should have to be 35. And after I delete 50 from this tree, I used inOrder function to check the updated tree. I got this:

[ 12 ] [ 35 ] [ 25 ] [ 58 ] [ 75 ] [ 87 ] [ 100 ] [ 125 ] [ 150 ] [ 168 ] [ 175 ] [ 180 ]

As you can see, the sequence is not correctly ordered.

I think the correct code for getMax should be:

node *getMax(node *root)
{
// If there's no leaf to the right, then this is the maximum key value
if (root->right == NULL)
return root;
else
// root->right = getMax(root->right);
return getMax(root->right);
}

Correct me if I was wrong, please.

Originally created by @bayegy on GitHub (Jul 12, 2020). Hi there, I am learning data structure. it's really helpful to find such a excellent project. Thanks for the excellent work. However, I found this code may not work correctly. https://github.com/TheAlgorithms/C/blob/08415b0f165d73f8cdf5443d2183b2b73b748650/data_structures/binary_trees/binary_search_tree.c#L65 let's say we have a tree like this ` node *root = NULL;` ` root = insert(root, 100);` ` root = insert(root, 50);` ` root = insert(root, 25);` ` root = insert(root, 12);` ` root = insert(root, 35);` ` root = insert(root, 75);` ` root = insert(root, 58);` ` root = insert(root, 87);` ` root = insert(root, 150);` ` root = insert(root, 125);` ` root = insert(root, 175);` ` root = insert(root, 168);` ` root = insert(root, 180);` When I want to delete 50 from this tree, getMax function returns 25 for the max data of the left subtree of node 50, which should have to be 35. And after I delete 50 from this tree, I used inOrder function to check the updated tree. I got this: > [ 12 ] [ 35 ] [ 25 ] [ 58 ] [ 75 ] [ 87 ] [ 100 ] [ 125 ] [ 150 ] [ 168 ] [ 175 ] [ 180 ] As you can see, the sequence is not correctly ordered. I think the correct code for getMax should be: `node *getMax(node *root)` `{` ` // If there's no leaf to the right, then this is the maximum key value` ` if (root->right == NULL)` ` return root;` ` else` ` // root->right = getMax(root->right);` ` return getMax(root->right);` `}` Correct me if I was wrong, please.

claunia referenced this issue

2026-01-29 15:10:50 +00:00

[PR #50] [CLOSED] Add: Binary to Octal conversion #267

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Reference: starred/C#50