package problems.medium;
import problems.utils.TreeNode;
import java.util.HashMap;
import java.util.Map;
/**
* Created by sherxon on 4/15/17.
*/
public class LargestBSTSubtree {
int max=0;
Map<TreeNode, Integer> map = new HashMap<>();
public int largestBSTSubtree(TreeNode root) {
if(root==null)return 0;
size(root);
go(root);
return max;
}
void go(TreeNode x){
if(x==null)return ;
if(check(x, Long.MIN_VALUE, Long.MAX_VALUE)){
max=Math.max(map.get(x), max);
}
go(x.left);
go(x.right);
}
boolean check(TreeNode x, long min, long max){
if(x==null)return true;
return x.val > min && x.val < max && check(x.left, min, x.val) && check(x.right, x.val, max);
}
int size(TreeNode x){
if(x==null)return 0;
if(map.containsKey(x))return map.get(x);
int size=size(x.left) + size(x.right)+1;
map.put(x, size);
return size;
}
}