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.

題意為：判斷兩棵二叉樹是否一樣。

C程式碼實現accepted。思路：暴力比較，程式碼個人覺得寫的不夠簡潔。先比較根節點，然後左右子樹。

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
bool isSameTree(struct TreeNode *p, struct TreeNode *q) {
    if(p==NULL && q==NULL) return true;
    if(p!=NULL && q==NULL) return false;
    if(p==NULL && q!=NULL) return false;
    if(p!=NULL && q!=NULL && p->val != q->val) return false;
    else
    return (isSameTree(p->left,q->left))&&(isSameTree(p->right,q->right)); 
    
}