Coding/BST_validate.java at main · shr100/Coding · GitHub

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//Link : https://leetcode.com/problems/validate-binary-search-tree/
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
classSolution {
publicbooleanisValidBST(TreeNoderoot) {
returndummy(root,Double.NEGATIVE_INFINITY,Double.POSITIVE_INFINITY);
 }
publicbooleandummy(TreeNodep,doublemin,doublemax){
if(p==null){
returntrue;
 }

if((p.val<=min)||(p.val>=max))
 {
returnfalse;
 }
booleanleftBST = dummy(p.left,min,p.val);
booleanrightBST = dummy(p.right,p.val,max);

if((leftBST&&rightBST)==false){
returnfalse;
 }


returntrue;
}
}