//100

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.

class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        //p,q may NULL
        if(p==NULL && q==NULL){
            return true;
        }
        if(p==NULL || q==NULL){
            return false;
        }
        //p,q is not NULL,recursion
        if(p->val == q->val){
            bool left=isSameTree(p->left,q->left);
            bool right=isSameTree(p->right,q->right);
            return left && right;
        } else{
            return false;
        }
    }
};