LeetCode-in-Java
872. Leaf-Similar Trees
Easy
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.
Example 1:
Input: root1 = [3,5,1,6,2,9,8,null,null,7,4], root2 = [3,5,1,6,7,4,2,null,null,null,null,null,null,9,8]
Output: true
Example 2:
Input: root1 = [1,2,3], root2 = [1,3,2]
Output: false
Constraints:
- The number of nodes in each tree will be in the range
[1, 200]. - Both of the given trees will have values in the range
[0, 200].
Solution
import com_github_leetcode.TreeNode;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
/*
* 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;
* }
* }
*/
public class Solution {
public boolean leafSimilar(TreeNode root1, TreeNode root2) {
List<Integer> list1 = new ArrayList<>();
List<Integer> list2 = new ArrayList<>();
preOrder(root1, list1);
preOrder(root2, list2);
// compare the lists
if (list1.size() != list2.size()) {
return false;
}
for (int i = 0; i < list1.size(); i++) {
if (!Objects.equals(list1.get(i), list2.get(i))) {
return false;
}
}
return true;
}
private void preOrder(TreeNode root, List<Integer> list) {
if (root != null) {
if (root.left == null && root.right == null) {
list.add(root.val);
}
preOrder(root.left, list);
preOrder(root.right, list);
}
}
}