leetcode: (100) Same Tree

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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.

方法：遍历两树，并比较结点的值

本题采用中序遍历的栈操作的非递归方法
/**
* 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) {
TreeNode *first,*second;
first = p;
second = q;
stack<TreeNode*> sta1;
stack<TreeNode*> sta2;
if((p==NULL&&q!=NULL)||(p!=NULL&&q==NULL)) return false;
while((p!=NULL&&q!=NULL)||(!sta1.empty()&&!sta2.empty()))
{
while(p!=NULL&&q!=NULL)
{
sta1.push(p);
sta2.push(q);
p=p->left;
q=q->left;
if((p==NULL&&q!=NULL)||(p!=NULL&&q==NULL)) return false;
}
if(!sta1.empty()&&!sta2.empty())
{
p=sta1.top();
sta1.pop();
q=sta2.top();
sta2.pop();
if(p->val!=q->val) return false;
p=p->right;
q=q->right;
if((p==NULL&&q!=NULL)||(p!=NULL&&q==NULL)) return false;
}
}
return true;
}
};