vardanator

// Assuming graph is connected 
// and a graph node is defined by this structure
// struct GraphNode {
//   T item;
//   vector<GraphNode*> children;
// }

// WARNING: untested code
void BreadthFirstSearch(GraphNode* node) // start node
{

vardanator

// 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)

vardanator

template <typename BlaBla>
class BST
{
public:
  // other code ...
  vector<BlaBla*> InOrderProduceVector()
  {
    vector<BlaBla*> result;
    result.reserve(1000); // magic number, reserving a space to avoid reallocation on inserts
    InOrderProduceVectorHelper_(root_, result); // passing vector by reference

vardanator

// 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)
{
  // 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 in-order traversing the tree

vardanator

// Cached representation of an Item
// Full Item object (with title, description, comments etc.) 
// could be fetched from the database
struct Item
{
  // ID_TYPE is the type of Item's unique id, might be an integer, or a string
  ID_TYPE id;
  int rating;
};

vardanator

// struct TreeNode {
//   T item;
//   TreeNode* left;
//   TreeNode* right;
// }

// you cann pass a callback function to do whatever you want to do with the node's value
// in this particular example we are just printing its value.

// node is the "starting point", basically the first call is done with the "root" node

vardanator

// struct ListNode {
//   ListNode* next;
//   T item;
// }; 

void TraverseRecursive(ListNode* node) // starting node, most commonly the list 'head'
{
  if (!node) return; // stop
  std::cout << node->item;
  TraverseRecursive(node->next); // recursive call

vardanator

// Warning: a bunch of pseudocode ahead

void RangeInsertIntoTimelines(vector<long> user_ids, long tweet_id)
{
  for (auto id : user_ids) {
    InsertIntoUserTimeline(id, tweet_id);
  }
}

void DeliverATweet(User* author, Tweet* tw)

vardanator

// 'author' represents the User object, at this point we are interested only in author.id
//
// 'tw' is a Tweet object, at this point we are interested only in 'tw.id' 

void DeliverATweet(User* author, Tweet* tw)
{
  // we assume that 'tw' object is already stored in a database
  
  // 1. Get the list of user's followers (author of the tweet)
  vector<User*> user_followers = GetUserFollowers(author->id);

vardanator

// 'author' represents the User object, at this point we are interested only in author.id
//
// 'tw' is a Tweet object, at this point we are interested only in 'tw.id' 

void DeliverATweet(User* author, Tweet* tw)
{
  // we assume that 'tw' object is already stored in a database
  
  // 1. Get the list of user's followers (author of the tweet)
  vector<User*> user_followers = GetUserFollowers(author->id);