[LeetCode] NO. 100 Same Tree

[题目] 

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

 

[题目解析]  二叉树的问题，转化成当前节点与左子树，右子树问题。注意一些临界条件的判断。

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if(null == p && null == q) return true;
        if(null != p && null != q){
            return (p.val == q.val && isSameTree(p.left,q.left) && isSameTree(p.right,q.right));
        }else{
            return false;
        }
    }
}