100.判断两个二叉树是否完全相等 Same Tree

递归实现

static public bool IsSameTree(TreeNode root1, TreeNode root2) {
	if (root1 == null && root2 == null) {
		return true;
	}
	if ((root1 == null && root2 != null) || (root1 != null && root2 == null)) {
		return false;
	}
	if (root1.val != root2.val) {//判断每个节点的值是否相等，如果去除此判断，则判断两个二叉树是否结构相等
		return false;
	}
	return IsSameTree(root1.left, root2.left) && IsSameTree(root1.right, root2.right);
}

非递归实现方式

bool  BTreeCompare（BTreeNode_t *pRoot1, BTreeNode_t *pRoot2)  
{  
    if( pRoot1 == NULL && pRoot2 == NULL )  
        return false;  
  
  
    queue <BTreeNode_t *> que1;  
    queue <BTreeNode_t *> que2;  
  
  
    que1.push(pRoot1);  
    que2.push(pRoot2);  
  
  
    int curLevelNodeTotal1 = 0;  
    int curLevelNodeTotal2 = 0;  
  
  
    bool flag = true; //作为比较不一致时跳出标识  
    while( ( !que1.empty()) && ( !que2.empty())) //当两个队列均不为空时，才进行比较  
    {  
        curLevelNodeTotal1 = que1.size();  //获取树1的当前层节点总数  
        curLevelNodeTotal2 = que2.size(); //获取树2的当前层节点总数  
        if( curLevelNodeTotal1 != curLevelNodeTotal2){  
            flag = false;//当前层节点总数都不一致，不需要比较了，直接跳出  
            break;  
        }  
        int cnt1 = 0;//遍历本层节点时的计数器  
        int cnt2 = 0;  
        while( cnt1 < curLevelNodeTotal1  && cnt2 < curLevelNodeTotal2){  
            ++cnt1;  
            ++cnt2;  
            pRoot1 = que1.front();  
            que1.pop();  
            pRoot2 = que2.front();  
            que2.pop();  
  
            //比较当前节点中数据是否一致  
            if( pRoot1->m_pElemt != pRoot2->m_pElemt ){  
                flag = false;  
                break;  
            }  
            //判断pRoot1和pRoot2左右节点结构是否相同  
            if( ( pRoot1->m_pLeft != NULL && pRoot2->m_pLeft == NULL )    ||  
                ( pRoot1->m_pLeft == NULL && pRoot2->m_pLeft != NULL )    ||  
                ( pRoot1->m_pRight != NULL && pRoot2->m_pRight == NULL )    ||  
                ( pRoot1->m_pRight == NULL && pRoot2->m_pRight != NULL )  
            ){  
                flag = false;  
                break;  
            }  
   
            //将左右节点入队  
            if( pRoot1->m_pLeft != NULL )  
                que1.push( pRoot1->m_pLeft);  
            if( pRoot1->m_pRight != NULL )  
                que1.push( pRoot1->m_pRight);  
            if( pRoot2->m_pLeft != NULL )  
                que2.push( pRoot2->m_pLeft);  
            if( pRoot2->m_pRight != NULL )  
                que2.push( pRoot2->m_pRight);  
        }  
  
  
        if( flag == false )  
            break;  
    }  
  
    //如果比较标志为false，则不相同  
    if( flag == false ){  
        while( !que1.empty() )  
            que1.pop();  
        while( !que2.empty())  
            que2.pop();  
  
  
        return false;  
    }  
  
  
    return true;  
}  

null