# non-recursive. two queue Iteration

• ``````
/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool isSameTree(TreeNode* p, TreeNode* q) {
if(p==NULL && q != NULL) return false;
if(p!=NULL && q == NULL) return false;
if(p==NULL && q == NULL) return true;
if(p->val != q->val) return false;

queue<TreeNode*> pnode,qnode;
pnode.push(p);
qnode.push(q);

while(!pnode.empty() && !qnode.empty())
{
int np=pnode.size();
int nq=qnode.size();
if (np != nq)
{
return false;
}

for(int i=0;i<np;i++)
{
TreeNode *p1=pnode.front();
pnode.pop();
TreeNode *q2=qnode.front();
qnode.pop();

if(p1->val!=q2->val) return false;

if(p1->left!=NULL) pnode.push(p1->left);
if(q2->left!=NULL) qnode.push(q2->left);

//这里判断长度相等很巧妙，不然左右子树难以判断。
if(pnode.size()!=qnode.size()) return false;

if(p1->right!=NULL) pnode.push(p1->right);
if(q2->right!=NULL) qnode.push(q2->right);

}
}

if (pnode.empty()&!qnode.empty() || !pnode.empty()&qnode.empty()) return false;
return true;

}
};

~~~

~~~``````

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