题解 | #对称的二叉树#非递归dfs实现

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) {
        if(pRoot == null){
            return true;
        }
        Stack<TreeNode> stack = new Stack();
        stack.push(pRoot.left);
        stack.push(pRoot.right);
        while(!stack.isEmpty()){
            TreeNode right = stack.pop();
            TreeNode left = stack.pop();
            if(left == null && right == null){
                continue;
            }
            if(left == null || right == null){
                return false;
            }
            if(left.val != right.val){
                return false;
            }
            stack.push(left.left);
            stack.push(right.right);
            stack.push(left.right);
            stack.push(right.left);
        }
        return true;
    }
}