【23】二叉树的相关操作

一. 二叉树的结点表示

struct BinaryTreeNode{
    int value;
	BinaryTreeNode *lson;
	BinaryTreeNode *rson;
};

//前序遍历算法
void PrintPreOrder(BinaryTreeNode *root){
	if(root != NULL){
		cout<<root->value<<endl;
		PrintPreOrder(root->lson);
		PrintPreOrder(root->rson);
	}
}
//中序遍历算法
void PrintInOrder(BinaryTreeNode *root){
	if(root != NULL){
		PrintInOrder(root->lson);
		cout<<root->value<<endl;
		PrintInOrder(root->rson);
	}
}
//后序遍历算法
void PrintPostOrder(BinaryTreeNode *root){
	if(root != NULL){
		PrintPostOrder(root->lson);
		PrintPostOrder(root->rson);
		cout<<root->value<<endl;
	}
}

//层序遍历算法
void PrintStageOrder(BinaryTreeNode *root){
	if(root == NULL){
	    return;
	}
	queue<BinaryTreeNode*>q;
	q.push(root);
	while(!q.empty()){
		BinaryTreeNode *tmpNode = q.front();
		cout<<tmpNode->value<<endl;
		q.pop();
		if(tmpNode->lson != NULL){
			q.push(tmpNode->lson);
		}
		if(tmpNode->rson != NULL){
			q.push(tmpNode->rson);
		}
	}
}

int GetTreeNodeNumber(BinaryTreeNode *root){
	if(root == NULL){
	   return 0;
	}
	return 1+GetTreeNodeNumber(root->lson)+GetTreeNodeNumber(root->rson);
}

int GetTreeHigh(BinaryTreeNode *root){
	if(root == NULL){
	   return 0;
	}
	int lsonHigh = GetTreeHigh(root->lson);
	int rsonHigh = GetTreeHigh(root->rson);
	return (lsonHigh+1 < rsonHigh+1 ? rsonHigh+1 : lsonHigh+1);
}

bool IsEqual(BinaryTreeNode *root1, BinaryTreeNode *root2){
	if(root1 == NULL && root2 == NULL){
	   return true;
	}
	if(root1 != NULL && root2 != NULL //一定要是两个根结点都不为空
		&&root1->value == root2->value
		&& IsEqual(root1->lson, root2->lson)
		&& IsEqual(root1->rson, root2->rson)){
	   return true;
	}
	else{
	   return false;
	}
}

void ConvertLsonAndRson(BinaryTreeNode *root){
	if(root == NULL){
	   return;
	}
	BinaryTreeNode *tmpNode = root->lson;
	root->lson = root->rson;
	root->rson = tmpNode;
	ConvertLsonAndRson(root->lson);
	ConvertLsonAndRson(root->rson);
}

int GetLeafNodeNumber(BinaryTreeNode *root){
	if(root == NULL){
	   return 0;
	}
        //到了叶子节点
	if(root->lson == NULL && root->rson == NULL){
	   return 1;
	}
	else{
           return GetLeafNodeNumber(root->lson)
		+GetLeafNodeNumber(root->rson);
	}
}

bool IsSubTree(BinaryTreeNode* root1, BinaryTreeNode* root2){
    //如果root2为NULL肯定是root1的子结构
	if(root2 == NULL){
	   return true;
	}
	//如果root2不为NULL但root1为NULL肯定不是
	if(root1 == NULL){
	   return false;
	}
	//如果两个根结点都不为空但是值不同也不是
	if(root1->value != root2->value){
	   return false;
	}
	else{
		return IsSubTree(root1->lson, root2->lson)
			&&IsSubTree(root1->rson, root2->rson);
	}
}