sameTree.java

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

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

Example 1:

Input:     1         1
          / \       / \
         2   3     2   3

        [1,2,3],   [1,2,3]

Output: true
Example 2:

Input:     1         1
          /           \
         2             2

        [1,2],     [1,null,2]

Output: false
Example 3:

Input:     1         1
          / \       / \
         2   1     1   2

        [1,2,1],   [1,1,2]

Output: false
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/**
 * 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(p == null && q == null){
             return true;
         }else if(p == null || q == null){
             return false;
         }else{
             return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
         }
     }
 }