Largest BST

class Test{
    int minVal;
    int maxVal;
    int size;
    
    Test(int mi, int ma, int s){
        minVal = mi;
        maxVal =  ma;
        size = s;
    }
}

class Solution{
    
    // Return the size of the largest sub-tree which is also a BST
    static int largestBst(Node root)
    {
        // Write your code here
        return solve(root).size;
    }
    
    static Test solve(Node root){
        if(root == null)
        return new Test(Integer.MAX_VALUE, Integer.MIN_VALUE, 0);
        
        Test left = solve(root.left);
        Test right = solve(root.right);
        
        if(left.maxVal < root.data && root.data < right.minVal){
            return new Test(Math.min(root.data, left.minVal),
            Math.max(root.data, right.maxVal),
            left.size + right.size + 1);
        }
        return new Test(Integer.MIN_VALUE, Integer.MAX_VALUE, 
        Math.max(left.size, right.size));
    }
    
}