检查两棵二叉树是否等价。等价的意思是说，首先两棵二叉树必须拥有相同的结构，并且每个对应位置上的节点上的数都相等。
image.png
/**
* Definition of TreeNode:
* class TreeNode {
* public:
* int val;
* TreeNode *left, *right;
* TreeNode(int val) {
* this->val = val;
* this->left = this->right = NULL;
* }
* }
*/
class Solution {
public:
/**
* @aaram a, b, the root of binary trees.
* @return true if they are identical, or false.
*/
bool isIdentical(TreeNode* a, TreeNode* b) {
// Write your code here
if(a==NULL&&b==NULL)
return true;
if((a!=NULL&&b==NULL)||(a==NULL&&b!=NULL))
return false;
if(a->val==b->val)
{
return isIdentical(a->left, b->left) && isIdentical(a->right, b->right);
}
else{
return false;
}
}
};
