958. Check Completeness of a Binary Tree

Dear 丶 2023-06-01 12:54 16阅读 0赞

958. Check Completeness of a Binary Tree
    
    //https://leetcode.com/problems/check-completeness-of-a-binary-tree/description/
    
    class TreeNode(var `val`: Int) {
        var left: TreeNode? = null
        var right: TreeNode? = null
    }
    
    class Solution {
        fun isCompleteTree(root: TreeNode?): Boolean {
            if (root == null) {
                return false
            }
            val linkedList = LinkedList<TreeNode>()
            linkedList.add(root)
            while (linkedList.peek()!=null) {
                //if popped node is not null, then add its left and right child, no matter if they are null or not
                val cur = linkedList.poll()
                linkedList.offer(cur.left)
                linkedList.offer(cur.right)
            }
            //get right node first
            while (linkedList.isNotEmpty() && linkedList.peek()==null){
                linkedList.poll()
            }
            return linkedList.isEmpty()
        }
    }

转载于:https://www.cnblogs.com/johnnyzhao/p/11429381.html

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