Validate Binary Search Tree leetcode https://leetcode.com/problems/validate-binary-search-tree/ Java Solution

ValidBinarySearchTree.java

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
 public  boolean isValidBST(TreeNode root){
        if(root == null){
            return true;
        }
        boolean isLeftBranchValid = true;
        boolean isRightBranchValid = true;
        if(root.left != null){
            isLeftBranchValid = isValidBranch(root.left,Long.MIN_VALUE,root.val);
        }

        if(root.right != null){
            isRightBranchValid = isValidBranch(root.right,root.val,Long.MAX_VALUE);
        }

        return (isLeftBranchValid && isRightBranchValid);
    }

    public static boolean isValidBranch(TreeNode branch,long minLimit,long maxLimit){
        if(branch.val <= minLimit || branch.val >= maxLimit){
            return false;
        }
        boolean isLeftBranchValid = true;
        boolean isRightBranchValid = true;
        if(branch.left != null){
            isLeftBranchValid = isValidBranch(branch.left,minLimit,branch.val);
        }

        if(branch.right != null){
            isRightBranchValid = isValidBranch(branch.right,branch.val,maxLimit);
        }

        return (isLeftBranchValid && isRightBranchValid);
    }
}