题解 | #求二叉树的层序遍历#

package suanfa.tree;

import java.util.ArrayList;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.LinkedBlockingDeque;

/**

• 二叉树的层序遍历

• /
  public class LevelOrder {

  /**

  • 二叉树的层序遍历 依赖queue实现

  • @param root

  • @return

  • /
    public static List<List<integer>> levelOrder(TreeNode root) {
    List<List<integer>> list = new ArrayList<>();</integer></integer>

    Queue<treenode> queue = new LinkedBlockingDeque<>();
    queue.add(root);</treenode>

    while (!queue.isEmpty()) {

      List<Integer> subList = new ArrayList<>();
    
      int currentLevelSize = queue.size();
      //遍历每一层 
      for (int i = 1; i < currentLevelSize; i++) {
    
          TreeNode tmpNode = queue.poll();
          subList.add(tmpNode.val);
    
          if (tmpNode.left != null) {
              queue.offer(tmpNode.left);
          }
    
          if (tmpNode.right != null) {
              queue.offer(tmpNode.right);
          }
      }
      list.add(subList);

    }

    return list;
    }

static class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;

    public int getVal() {
        return val;
    }

    public void setVal(int val) {
        this.val = val;
    }

    public TreeNode getLeft() {
        return left;
    }

    public void setLeft(TreeNode left) {
        this.left = left;
    }

    public TreeNode getRight() {
        return right;
    }

    public void setRight(TreeNode right) {
        this.right = right;
    }
}

}