LeetCode – Tree – Leaf-Similar Trees

Consider all the leaves of a binary tree.  From left to right order, the values of those leaves form a leaf value sequence.

For example, in the given tree above, the leaf value sequence is (6, 7, 4, 9, 8).

Two binary trees are considered leaf-similar if their leaf value sequence is the same.

Return true if and only if the two given trees with head nodes root1 and root2 are leaf-similar.

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    List<Integer> r1_leafValues = new ArrayList<Integer>();
    List<Integer> r2_leafValues = new ArrayList<Integer>();
    
    public boolean leafSimilar(TreeNode root1, TreeNode root2) {
        boolean result = true;
        
        getLeafValues(root1,r1_leafValues);
        getLeafValues(root2,r2_leafValues);
        
        //System.out.println(r1_leafValues);
        //System.out.println(r2_leafValues);
        
        if(r1_leafValues.size() != r2_leafValues.size()) result=false;
        else{
            for(int i=0;i<r1_leafValues.size();i++){
                if(r1_leafValues.get(i) != r2_leafValues.get(i)) result = false;
            }
        }
        return result;
    }
    
    public void getLeafValues(TreeNode root, List leafValues){
    if(root.left == null && root.right == null){
        leafValues.add(root.val);
    }
    if(root.left !=null){
        getLeafValues(root.left,leafValues);
    }
    if(root.right != null){
        getLeafValues(root.right,leafValues);
    }            
    }
}