题解 | #对称的二叉树#

import java.util.*;

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

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

}

} */ public class Solution { boolean isSymmetrical(TreeNode pRoot) { if (pRoot == null){ return true; } if ((pRoot.left == null) != (pRoot.right == null)){ return false; } if (pRoot.left == null){ return true; } List toBeTraversed = new ArrayList<>(); toBeTraversed.add(pRoot.left); toBeTraversed.add(pRoot.right);

    while(toBeTraversed.size() > 0){
        TreeNode candidateOne = toBeTraversed.get(0);
        TreeNode candidateTwo = toBeTraversed.get(1);
        if (candidateOne.val != candidateTwo.val){
            return false;
        }
        toBeTraversed.remove(0);
        toBeTraversed.remove(0);
        
        if ((candidateOne.left == null) == (candidateTwo.right == null)){
            if (candidateOne.left != null){
                toBeTraversed.add(candidateOne.left);
                toBeTraversed.add(candidateTwo.right);
            }
        }else{
            return false;
        }
        
        if ((candidateOne.right == null) == (candidateTwo.left == null)){
            if (candidateOne.right != null){
                toBeTraversed.add(candidateOne.right);
                toBeTraversed.add(candidateTwo.left);
            }
        }else{
            return false;
        }
    }
    return true;
}

}