Design an algorithm to determine whether a given binary tree is a two-fork sort tree (all the keywords of a binary tree are positive integers)

Thought: For the two-fork sort tree , in which the sequence traversal sequence is an ascending ordered sequence , so, for a given two-fork tree in the middle sequence traversal, if the previous value can always be kept smaller than the latter value, then the two fork tree is a binary sort tree. the algorithm is as follows:

KeyType predt=0; //predt is a global variable that holds the pre-order value of the current node, and the initial value is the minimum

int Judgebst (Bstnode *bt)

{

Returns 1 indicates a binary sort tree, and returns 0 that is not

int b1,b2;

if (bt==null)

return 1;

Else

{

B1=judgebst (Bt->lchild); //Judge left subtree

if (b1==0| | Predt>=bt->key)

return 0;

predt=bt->key; //Save the current node's keywords

B2=judgebst (Bt->rchild); //Judging Right sub-tree

return B2;

}

}

Note: if the middle sequence of a binary tree is an ordered sequence, then the two-fork tree must be a binary sort tree.

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Design an algorithm to determine whether a given binary tree is a two-fork sort tree (all the keywords of a binary tree are positive integers)