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.

广度优先遍历，考察两棵树中每一个的值以及左右孩子的值是否相等。

Program Runtime: 8 milli secs

1 /** 2  * Definition for binary tree 3  * struct TreeNode { 4  *     int val; 5  *     TreeNode *left; 6  *     TreeNode *right; 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8  * }; 9  */10 class Solution {11 public:12     bool isSameTree(TreeNode *p, TreeNode *q) {13         // Start typing your C/C++ solution below14         // DO NOT write int main() function15         if(q == p){16             return true;17         }18         queue
     
       qq, qp;19         if(NULL == p && NULL == q){20             return true;21         }else if(NULL != p && NULL != q){22             qq.push(q);23             qp.push(p);24         }else{25             return false;26         }27         while(qq.size() != 0 && qp.size() != 0){28             TreeNode *curp = qp.front();29             qp.pop();30             TreeNode *curq = qq.front();31             qq.pop();32             if(curq->val != curp->val){33                 return false;34             }35             if(curp->left && curq->left) {36                 if(curp->left->val != curq->left->val){37                     return false;38                 }39                 qp.push(curp->left);40                 qq.push(curq->left);41             }else if(curp->left != NULL && curq->left == NULL){42                 return false;43             }else if(curp->left == NULL && curq->left != NULL){44                 return false;45             }46             if(curp->right && curq->right) {47                 if(curp->right->val != curq->right->val){48                     return false;49                 }50                 qp.push(curp->right);51                 qq.push(curq->right);52             }else if(curp->right != NULL && curq->right == NULL){53                 return false;54             }else if(curp->right == NULL && curq->right != NULL){55                 return false;56             }57         }58         if(qq.size() != 0 || qp.size() != 0){59             return false;60         }61         return true;62     }63 };