manojnaidu619

N+1 query problem

• ORMs make it easy to a query per loop iteration, which we want to avoid

eager_load

• single query (left outer join)
• can reference the other table's columns in where

preload

• a few queries (one per table)
• typically faster

manojnaidu619

class Node:
  def __init__(self, data):
    self.data = data
    self.next = None

class LinkedList:
  def __init__(self):
    self.head = None

  def form_ll(self, length):

manojnaidu619

Rails Deployment to AWS EC2

Stack : (Nginx + Phusion Passenger + Postgresql)

By Manoj Naidu

Here is the Video Tutorial

• Step -1

  To Launch an EC2 instance from aws console with all the credentials and configurations hooked.

• Step-2

manojnaidu619

class PaytmController < ApplicationController
  skip_before_action :verify_authenticity_token

  def paytm
    @checksum = new_pg_checksum(params, MERCHANT_KEY)          # MERCHANT_KEY = your Merchant key
  end

  def handle_payment
    if params["CHECKSUMHASH"]
      paytmHash = Hash.new

manojnaidu619

require 'contentful'

client = Contentful::Client.new(
  space: '<spacd_id>',
  access_token: '<access-token>',
  dynamic_entries: :auto
)

entries = client.entries          # For grabbing entries
entries.each do |entry|

manojnaidu619

queue<TreeNode*> q;         // To store the node addresses
vector<int> result;         // To store the values in the node
result.push_back(root->val);
q.push(root);
while (!q.empty()) { 
  node = q.front();
  q.pop();  
  if(node->left){
    result.push_back(node->left->val);
    q.push(node->left);

manojnaidu619

#include <iostream>
using namespace std;

struct Node{
    int data;
    struct Node *next;
};

int hash_(int key)
{

manojnaidu619

#include <iostream>
using namespace std;

struct Node{
    int data;
    struct Node *next;
};


int main(){

manojnaidu619

#include <iostream>
#include <vector>
using namespace std;

vector <int> a = {0};

void insert(int ele){
    int temp;
    a.push_back(ele);
    long last = a.size()-1;

manojnaidu619

=begin  
687.to_s(2)  # "1010101111"
"1010101111".to_i(2)   # 687
=end

def find_complement(num)
    num = num.to_s(2).chars
    num.map!{|i| i.to_i}
    for x in 0..num.size-1 do 
     if num[x]==0