Add Bootstrap 4 to your Ruby on Rails 6 application

Somnath.geek — Sat, 14 Mar 2020 09:49:32 +0000

Step 1: Using Yarn:

yarn add bootstrap@4.3.1 jquery popper.js

package.json file should look like this

"dependencies": {
    "@rails/actioncable": "^6.0.0",
    "@rails/activestorage": "^6.0.0",
    "@rails/ujs": "^6.0.0",
    "@rails/webpacker": "4.2.2",
    "bootstrap": "4.3.1",
    "jquery": "^3.4.1",
    "popper.js": "^1.16.1",
    "turbolinks": "^5.2.0"
  },

Step 2: Head to config/webpack/environment.js file and add these lines

const { environment } = require('@rails/webpacker')

const { environment } = require('@rails/webpacker')

const webpack = require("webpack")

environment.plugins.append("Provide", new webpack.ProvidePlugin({

$: 'jquery',

jQuery: 'jquery',

Popper: ['popper.js', 'default']

}))

module.exports = environment

Step 3 : Head to app/assets/stylesheets/application.css and add these lines

*= require bootstrap

*= require_tree .

*= require_self

Congratulation! You have successfully installed Bootstrap 4 😀

Two Sum solved in javascript

Somnath.geek — Sun, 29 Dec 2019 08:05:14 +0000

Two Sum : Javascript

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

Code:

 var twoSum = function(nums, target) {
    //hash table
    var hash = {};

    for(let i=0; i<=nums.length; i++){
      //current number
        var currentNumber = nums[i];
        //difference in the target and current number
        var requiredNumber = target - currentNumber;
        // find the difference number from hashTable
        const index2 = hash[requiredNumber];

        // if number found, return index 
        // it will return undefined if not found
        if(index2 != undefined) {
            return [index2, i]
        } else {
           // if not number found, we add the number into the hashTable
            hash[currentNumber] = i;

        }
    }
};

In detail:

Declare a empty hash table
Loop through the array
Store the current number in a variable
Find the difference between the the target number and the current number
Search for the difference number from the hash table
If number found, return the index of the first number and the search number
If not found, add the number into the hash table and continues for loop checking.

Conclusion:

Hashmap is the optimal solution as the average search time complexity is O(1)

Runtime	Memory
84 ms	35.5 MB

DEV Community: Somnath.geek