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 {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param pRoot TreeNode类 
     * @return bool布尔型
     */
    public boolean isSymmetrical (TreeNode pRoot) {
        // write code here
        if(pRoot == null) return true;
        return comp(pRoot.left,pRoot.right);
    }
    private boolean comp(TreeNode left,TreeNode right){
        if(left == null&&right != null) return false;
        if(right == null&&left!= null)  return false;
        if(left == null && right == null) return true;
        if(left.val == right.val){
            return comp(left.left,right.right)&&comp(left.right,right.left);
        }
        return false; 
    }
}

正常使用递归来写，if判断部分可以简化