傻瓜教程：手把手教你解決多個應用例項（附程式碼、手繪圖）
阿新 • • 發佈：2019-02-14
// Reminder: this is pseudocode, no bother with "const&", "std::" or others
// forgive me C++ fellows
template <typename BlaBla>
class BST
{
public:
// other code ...
vector<BlaBla*> ReverseInOrderProduceVector(int offset, int limit)
{
vector<BlaBla*> result;
result.reserve(limit);
// passing result vector by reference
// and passing offset and limit
ReverseInOrderProduceVectorHelper_(root_, result, offset, limit);
return result;
}
protected:
// takes a reference to vector
// skips 'offset' nodes and inserts up to 'limit' nodes
void ReverseInOrderProduceVectorHelper_(BSTNode* node, vector<BlaBla*>& destination, int offset, int limit)
{
if (!node) return;
if (limit == 0) return;
--offset; // skipping current element
ReverseInOrderProduceVectorHelper_(node->right, destination, offset, limit);
if (offset <= 0) { // if skipped enough, insert
destination.push_back(node->value);
--limit; // keep the count of insertions
}
ReverseInOrderProduceVectorHelper_(node->left, destination, offset, limit);
}
private:
BSTNode* root_;
};
// ... other possibly useful code
// this is a pseudocode, that's why I didn't bother with "const&"'s and "std::"'s
// though it could have look better, forgive me C++ fellows
vector<Item*> GetItemsByKeywordInSortedOrder(string keyword, offset, limit) // pagination using offset and limit
{
// assuming IndexTable is a big hashtable mapping keywords to Item BSTs
BST<Item*> items = IndexTable[keyword];
// suppose BST has a function InOrderProduceVector(), which creates a vector and
// inserts into it items fetched via reverse in-order traversing the tree
// to get items in descending order (starting from the highest rated item)
vector<Item*> sorted_result = items.ReverseInOrderProduceVector(offset, limit);
return sorted_result;
}
// forgive me C++ fellows
template <typename BlaBla>
class BST
{
public:
// other code ...
vector<BlaBla*> ReverseInOrderProduceVector(int offset, int limit)
{
vector<BlaBla*> result;
result.reserve(limit);
// passing result vector by reference
// and passing offset and limit
ReverseInOrderProduceVectorHelper_(root_, result, offset, limit);
return result;
}
protected:
// takes a reference to vector
// skips 'offset' nodes and inserts up to 'limit' nodes
void ReverseInOrderProduceVectorHelper_(BSTNode* node, vector<BlaBla*>& destination, int offset, int limit)
{
if (!node) return;
if (limit == 0) return;
--offset; // skipping current element
ReverseInOrderProduceVectorHelper_(node->right, destination, offset, limit);
if (offset <= 0) { // if skipped enough, insert
destination.push_back(node->value);
--limit; // keep the count of insertions
}
ReverseInOrderProduceVectorHelper_(node->left, destination, offset, limit);
}
private:
BSTNode* root_;
};
// ... other possibly useful code
// this is a pseudocode, that's why I didn't bother with "const&"'s and "std::"'s
// though it could have look better, forgive me C++ fellows
vector<Item*> GetItemsByKeywordInSortedOrder(string keyword, offset, limit) // pagination using offset and limit
{
// assuming IndexTable is a big hashtable mapping keywords to Item BSTs
BST<Item*> items = IndexTable[keyword];
// suppose BST has a function InOrderProduceVector(), which creates a vector and
// inserts into it items fetched via reverse in-order traversing the tree
// to get items in descending order (starting from the highest rated item)
vector<Item*> sorted_result = items.ReverseInOrderProduceVector(offset, limit);
return sorted_result;
}