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872. Leaf-Similar Trees

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Description

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], root2 = [1]
Output: true

Example 3:

Input: root1 = [1], root2 = [2]
Output: false

Example 4:

Input: root1 = [1,2], root2 = [2,2]
Output: true

Example 5:

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].

Solutions

Python3

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def leafSimilar(self, root1: TreeNode, root2: TreeNode) -> bool:
        def dfs(root, leaves):
            if root is None:
                return
            if root.left is None and root.right is None:
                leaves.append(root.val)
                return
            dfs(root.left, leaves)
            dfs(root.right, leaves)
        l1, l2 = [], []
        dfs(root1, l1)
        dfs(root2, l2)
        return l1 == l2

Java

/**
 * 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;
 *     }
 * }
 */
class Solution {
    public boolean leafSimilar(TreeNode root1, TreeNode root2) {
        List<Integer> l1 = new ArrayList<>();
        List<Integer> l2 = new ArrayList<>();
        dfs(root1, l1);
        dfs(root2, l2);
        return l1.equals(l2);
    }

    private void dfs(TreeNode root, List<Integer> leaves) {
        if (root == null) return;
        if (root.left == null && root.right == null) {
            leaves.add(root.val);
            return;
        }
        dfs(root.left, leaves);
        dfs(root.right, leaves);
    }
}

Go

func leafSimilar(root1 *TreeNode, root2 *TreeNode) bool {
	var l1, l2 []int
	if root1 != nil {
		dfs(root1, &l1)
	}
	if root2 != nil {
		dfs(root2, &l2)
	}
	return reflect.DeepEqual(l1, l2)
}

func dfs(root *TreeNode, leaves *[]int) {
	if root.Left == nil && root.Right == nil {
		*leaves = append(*leaves, root.Val)
	} else {
		if root.Left != nil {
			dfs(root.Left, leaves)
		}
		if root.Right != nil {
			dfs(root.Right, leaves)
		}
	}
}

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