[Leetcode]101. Symmetric Tree

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

唔。还是递归，很容易的一个题

public class Solution {
    public boolean isSymmetric(TreeNode root) {
        if(root==null) return true;
        return isMirror(root.left,root.right);
    }
    public boolean isMirror(TreeNode p, TreeNode q) {
        if(p==null && q==null) return true;
        if(p==null || q==null) return false;
        return (p.val==q.val) && isMirror(p.left,q.right) && isMirror(p.right,q.left);
    }
}