Largest binary search tree (BST) in a binary tree

Given a binary tree, find the largest Binary Search Tree (BST), where largest means BST with largest number of nodes in it. The largest BST may or may not include all of its descendants.

C++:
01 int LBST(Node* head, int min, int max, Node*& max_hd, int& cnt)
02 {
03     if(head==NULL)
04         return 0;
05     int cur_cnt=0;
06     if((head->value<=max)&&(head->value>=min)){
07         int left_cnt=LBST(head->left,min,head->value, max_hd, cnt);
08         int right_cnt=LBST(head->right,head->value,max,max_hd,cnt);
09         cur_cnt=left_cnt+right_cnt+1;
10         if(cur_cnt>cnt){
11             cnt=cur_cnt;
12             max_hd=head;
13         }
14     }
15     LBST(head->left,MIN,MAX, max_hd,cnt);
16     LBST(head->right,MIN,MAX,max_hd,cnt);
17     return cur_cnt;
18 }
Advertisements
This entry was posted in Binary search, Recursive, Tree. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s