LeetCode-101 对称二叉树--递归

对称二叉树--递归

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public boolean isSymmetric(TreeNode root) {
        if(root==null){
            return true;
        }
        return isSymmetric(root.left,root.right);
    }

    public boolean isSymmetric(TreeNode t1,TreeNode t2){
        if(t1==null && t2 ==null){
            return true;
        }
        if(t1==null || t2==null){
            return false;
        }
        if(t1.val !=t2.val){
            return false;
        }
        return isSymmetric(t1.left,t2.right) && isSymmetric(t1.right,t2.left);
    }
}