Algorithm
Problem Name: 965. Univalued Binary Tree
Problem Link: https://leetcode.com/problems/univalued-binary-tree/
A binary tree is uni-valued if every node in the tree has the same value.
Given the root of a binary tree, return true if the given tree is uni-valued, or false otherwise.
Example 1:
Input: root = [1,1,1,1,1,null,1] Output: true
Example 2:
Input: root = [2,2,2,5,2] Output: false
Constraints:
- The number of nodes in the tree is in the range
[1, 100]. 0 <= Node.val < 100
Code Examples
#1 Code Example with Java Programming
Code -
Java Programming
class Solution {
public boolean isUnivalTree(TreeNode root) {
if (root == null) {
return true;
}
return helper(root, root.val);
}
private boolean helper(TreeNode root, int val) {
if (root == null) {
return true;
}
if (root.val != val) {
return false;
}
return helper(root.left, val) && helper(root.right, val);
}
}
Input
root = [1,1,1,1,1,null,1]
Output
true
#2 Code Example with Javascript Programming
Code -
Javascript Programming
const isUnivalTree = function(root) {
const arr = []
dfs(root, arr)
for(let i = 1; i < arr.length; i++) {
if(arr[i] !== arr[i- 1]) return false
}
return true
};
function dfs(node, arr) {
if(node === null) return
arr.push(node.val)
dfs(node.left, arr)
dfs(node.right, arr)
}
Input
root = [1,1,1,1,1,null,1]
Output
true
#3 Code Example with Python Programming
Code -
Python Programming
class Solution:
def isUnivalTree(self, root):
"""
:type root: TreeNode
:rtype: bool
"""
if not root: return True
if root.left and root.left.val != root.val: return False
if root.right and root.right.val != root.val: return False
return self.isUnivalTree(root.left) and self.isUnivalTree(root.right)
Input
root = [2,2,2,5,2]
Output
false
#4 Code Example with C# Programming
Code -
C# Programming
namespace LeetCode
{
public class _0965_UnivaluedBinaryTree
{
public bool IsUnivalTree(TreeNode root)
{
if (root == null) return true;
if (root.left != null && root.left.val != root.val) return false;
if (root.right != null && root.right.val != root.val) return false;
return IsUnivalTree(root.left) && IsUnivalTree(root.right);
}
}
}
Input
root = [2,2,2,5,2]
Output
false