100. Same Tree

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.

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

其实后面的if判断还可以升级下，使用递归判断return
isSameTree(p.left, q.left)) && (isSameTree(p.right, q.right）读者可以想想这个