LeetCode - 919. 完全二叉树插入器 (数组）

数组

/** * 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 CBTInserter {
    
    private TreeNode[] treeArray;
    private int index;
    public CBTInserter(TreeNode root) {
    
         treeArray = new TreeNode[2000];
         index = 0;
         if(root!=null){
    
            Deque<TreeNode> deque = new LinkedList<>();
            deque.offerLast(root);
            while(deque.size() > 0){
    
                TreeNode peek = deque.pollFirst();
                if(peek.left!=null)
                  deque.offerLast(peek.left);
                if(peek.right!=null)
                  deque.offerLast(peek.right);
                treeArray[index++] = peek;
            }
         }
       
    }
    
    public int insert(int val) {
    
        int parent = (index - 1) / 2;
        int child = index;
        TreeNode node = new TreeNode(val);
        treeArray[index++] = node;
        if(parent>=0)
        {
    
            TreeNode pn = treeArray[parent];
            if(child % 2 == 1)
              pn.left = node;
            else
              pn.right = node;
        }
        return treeArray[parent].val;
    }
    
    public TreeNode get_root() {
    
         return treeArray[0];
    }
}

/** * Your CBTInserter object will be instantiated and called as such: * CBTInserter obj = new CBTInserter(root); * int param_1 = obj.insert(val); * TreeNode param_2 = obj.get_root(); */