Leetcode-Same Tree

LiBlog發表於2014-11-09
LeetCode

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.

Solution:

 1 /**
 2  * Definition for binary tree
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public boolean isSameTree(TreeNode p, TreeNode q) {
12         boolean res = isSameTreeRecur(p,q);
13         
14         return res;
15     }
16     
17     public boolean isSameTreeRecur(TreeNode left, TreeNode right){
18         if ((left==null&&right!=null)||(left!=null&&right==null))
19             return false;
20         
21         if (left==null&&right==null)
22             return true;
23         
24         if (left.val!=right.val)
25             return false;
26             
27         if (left.left==null&&left.right==null&&right.left==null&&right.right==null)
28             return true;
29         
30         boolean leftSame = isSameTreeRecur(left.left,right.left);
31         if (!leftSame)
32             return false;
33             
34         boolean rightSame = isSameTreeRecur(left.right,right.right);
35         if (!rightSame)
36             return false;
37         
38         return true;
39     }
40 }

Similar to the symmetric tree problem. Need to consider every possible situation carefully.

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