// Source : https://oj.leetcode.com/problems/same-tree/

// Author : Hao Chen

// Date : 2014-06-27

/**********************************************************************************

*

* 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.

*

*

**********************************************************************************/

/**

* Definition for binary tree

* struct TreeNode {

* int val;

* TreeNode *left;

* TreeNode *right;

* TreeNode(int x) : val(x), left(NULL), right(NULL) {}

* };

*/

class Solution {

public:

Solution(){

srand(time(NULL));

}

bool isSameTree(TreeNode *p, TreeNode *q) {

if (random()%2){

return isSameTree1(p, q);

}

return isSameTree2(p, q);

}

bool isSameTree1(TreeNode *p, TreeNode *q) {

if(!p && !q) return true;

if(!p || !q) return false;

return (p->val == q->val) &&

isSameTree(p->left, q->left) &&

isSameTree(p->right, q->right);

}

bool isSameTree2(TreeNode *p, TreeNode *q) {

queue<TreeNode*> q1, q2;

q1.push(p);

q2.push(q);

while (q1.size()>0 && q2.size()>0 ){

TreeNode* p1 = q1.front();

q1.pop();

TreeNode* p2 = q2.front();

q2.pop();

if (!p1 && !p2) continue;

if (!p1 || !p2) return false;

if ( p1->val != p2->val) {

return false;

}

q1.push(p1->left);

q2.push(p2->left);

q1.push(p1->right);

q2.push(p2->right);

}

return true;

}

};