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.

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 }
This entry was posted in Binary search, Recursive, Tree. Bookmark the permalink.

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