LeetCode之Univalued Binary Tree（K

问题：
A binary tree is univalued if every node in the tree has the same value.
Return true if and only if the given tree is univalued.

方法：
先保存根节点的val，然后递归遍历整个tree，如果有某个节点的val不等于根节点的val则返回false，否则返回true，遍历的结果即为最终结果。

具体实现：

class UnivaluedBinaryTree {
    // Definition for a binary tree node.
    class TreeNode(var `val`: Int = 0) {
        var left: TreeNode? = null
        var right: TreeNode? = null
    }

    private var uniValue = 0

    fun isUnivalTree(root: TreeNode?): Boolean {
        if(root == null) {
            return false
        } else {
            uniValue = root.`val`
            return isUnivalTreeInternal(root.left) && isUnivalTreeInternal(root.right)
        }
    }

    fun isUnivalTreeInternal(root: TreeNode?): Boolean {
        if(root == null) {
            return true
        } else {
            return isUnivalTreeInternal(root.left) && isUnivalTreeInternal(root.right) && root.`val` == uniValue
        }
    }
}

fun main(args: Array<String>) {

}

有问题随时沟通

具体代码实现可以参考Github