Range Sum of BST.java

https://leetcode.com/problems/range-sum-of-bst

/**
 * 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;
 *     }
 * }
 */

recursive solution
class Solution {
    int range_sum;
    public int rangeSumBST(TreeNode root, int L, int R) {
            range_sum =0;
            get_range_sum(root,L,R);
            return range_sum;
    }
    public void get_range_sum(TreeNode root,int L,int R){
        if(root!=null){
            if(root.val>=L && root.val<=R ){
                range_sum+=root.val;
            }
            if(root.val > L){
                get_range_sum(root.left,L,R);
            }
            if(root.val<R){
                get_range_sum(root.right,L,R);
            }
        }
    }
}
    
iterative solution
      int range_sum =0;
          Stack<TreeNode> stack = new Stack();
          stack.push(root);
        
        while(!stack.isEmpty()){
            TreeNode  node = stack.pop();
                if(node.val>=L && node.val<=R){
                    range_sum += node.val;
                }
                if(node.val>L && node.left!=null){
                    stack.push(node.left);
                }
                if(node.val<R && node.right!=null){
                    stack.push(node.right);
                }
        }
        return range_sum;