Leetcode 102 : 二叉树的层序遍历

布满荆棘的人生 2022-10-16 07:11 178阅读 0赞

https://leetcode-cn.com/problems/binary-tree-level-order-traversal/submissions/

考察点： 二叉树层次遍历、层次遍历中处理每层数据

import BasicDataStruct.TreeNode;
    
    import java.util.ArrayList;
    import java.util.LinkedList;
    import java.util.List;
    import java.util.Queue;
    
    public class Leetcode102MiddleOrderSearch {
        
    
        public static List<List<Integer>> inorderTraversal(TreeNode root) {
        
    
            List<List<Integer>> list = new ArrayList<>();
            Queue<TreeNode> queue = new LinkedList<>();
            queue.offer(root);
            while (!queue.isEmpty()) {
        
                int size = queue.size();
                List<Integer> subList = new ArrayList<>();
                for (int i = 0; i < size; i++) {
        
                    TreeNode node = queue.poll();
                    subList.add(node.getVal());
                    if (node.left != null) {
        
                        queue.add(node.left);
                    }
                    if (node.right != null) {
        
                        queue.add(node.right);
                    }
                }
                list.add(subList);
            }
            return list;
        }
    
    
        public static void main(String[] args) {
        
            TreeNode root = new TreeNode(1);
            root.left = new TreeNode(2);
            root.right = new TreeNode(3);
            root.left.left = new TreeNode(4);
            root.left.right = new TreeNode(5);
            root.right.left = new TreeNode(6);
            root.right.right = new TreeNode(7);
            System.out.println(inorderTraversal(root).toString());
        }
    
    }