题解 | #对称的二叉树#

在lc上做的移过来了，不是抄的。 双队列，一个从左向右，一个从右向左，注意判断空值。

/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
import java.util.*;
public class Solution {
    boolean isSymmetrical(TreeNode pRoot) {
        TreeNode root = pRoot;
        Queue<TreeNode> left = new LinkedList<>();
        Queue<TreeNode> right = new LinkedList<>();
        TreeNode lp;
        TreeNode rp;
        if(root == null){
            return true;
        }
        left.offer(root);
        right.offer(root);
        int r,l;
        
        while(!left.isEmpty()){
            r=0;
            l=0;
            lp = left.poll();
            rp = right.poll();
            if(lp.val != rp.val ){
                return false;
            }
            if(lp.left != null){
                l =1;
                left.offer(lp.left);
            }
            if(lp.right != null){
                r= 1;
                left.offer(lp.right);
            }
            if(rp.right == null && l==1){
                return false;
            }
            if(rp.left == null && r==1){
                return false;
            }
            if(rp.right != null){
                
                right.offer(rp.right);
            }
            if(rp.left !=null){
                right.offer(rp.left);
            }
        }
        return true;
    }
}