System Design

 






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Basics

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https://leetcode.com/problems/palindrome-linked-list/description/ https://www.w3schools.com/jsref/jsref_slice_array.asp   const arr=[1,2] ; console.log(arr.reverse().join()===arr.join()); ChatGPT The expression arr.reverse() reverses the order of elements in the arr array in place, meaning it modifies the original array. The arr.join() method converts the elements of the array into a string, with each element separated by a comma by default. In the given code, arr.reverse().join() returns a string representation of the reversed array. However, the original arr array has also been reversed because the reverse() method modifies the array directly. Therefore, arr.reverse().join() === arr.join() will evaluate to true because both sides of the comparison refer to the same array that has been reversed and then converted to a string. const newarr =arr; return newarr.reverse().join()===arr.join() ; ChatGPT In the code you provided, newarr is assigned the reference to the arr ...
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Arguments Passed in Functions

https://leetcode.com/problems/return-length-of-arguments-passed/editorial/ We need to count the number of arguments passed to function  argumentsLength . Here the arguments are passsed in the form of rest parameters. why do we need to pass it like that?  the rest parameter is a feature that allows a function to accept an indefinite number of arguments The rest parameter collects all the remaining arguments passed to a function into an array even if the number of arguments is not known in advance. If no additional arguments are passed, the rest parameter will be an empty array Syntax: function functionName ( ... args ) { // Function body } conventionally named  args  or  rest  to indicate its purpose. function sum ( ... args ) { let total = 0 ; for ( let number of args ) { total += number ; } return total ; } console . log ( sum ( 1 , 2 , 3 , 4 ) ) ; // Output: 10 console . log ( sum ( 5 , 10 , 15 ) ) ; // Output...
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Offset index of an array

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const numbers = [1,2,3,4]; const output =move(numbers,1,-1);  [2,1,3,5,4] console.log(output);  function move(array,index,offset){ } https://www.freecodecamp.org/news/swap-two-array-elements-in-javascript/   /**  * Move an element  * input ->[1,2,3,4,5];  * move(arr,index,offset)  *   * we should not modify the orignal array  *   * if not possible --> invalid  * move(input,0,-1)  *  */ const move =(arr,index,offset)=>{   const position =index+offset;      if(position>=arr.length||position<0){         return 'Invalid';   }      const clone =[...arr];   let element=clone.splice(index,1)[0];   clone.splice(position,0,element)   return clone; } const arr=[1,2,3,4,5]; console.log(move(arr,0,5))  
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