Question

Split the Number

IN JAVASCRIPT

Programming challenge description:

You are given a number N and a pattern. The pattern consists of lowercase latin letters and one operation "+" or "-". The challenge is to split the number and evaluate it according to this pattern e.g.
1232 ab+cd -> a:1, b:2, c:3, d:2 -> 12+32 -> 44

Input:

Your program should read lines from standard input. Each line contains the number and the pattern separated by a single whitespace. The number will be in range [100, 1000000000]. All test cases contain valid expressions (no leading zeros).

Output:

Print out the result of the pattern evaluation.

Test 1

Test InputDownload Test 1 Input

3413289830 a-bcdefghij

Expected OutputDownload Test 1 Input

-413289827

Test 2

Test InputDownload Test 2 Input

776 a+bc

Expected OutputDownload Test 2 Input

83

Answer 1

Solution:

//importing the readline module to allow taking standart input
const readline = require ('readline').createInterface ({
  input: process.stdin,
  output: process.stdout,
});
//prompting user to enter the requrired input
readline.question ('Enter the number and pattern: ',
//the entered value is stored in 'input' variable.
input => {
  //Step 1. Split the input by specifying whitespace character as the delimeter
  var splittedInput = input.split (' ');
  //the number is in the 0th index of splitted string
  var number = splittedInput[0];
  //the pattern is on the 1st index of splitted string
  var pattern = splittedInput[1];
  //decalring the digits array to store the digits of number
  var digits = [];
  //while loop to extract the digits and add them in the digits array
  while (number != 0) {
    digit = number % 10;
    digits.push (digit);
    //Math.floor is used to make sure that number remains in integer form
    number = Math.floor (number / 10);
  }
  //reversing the digits array to get the actual order of digits.
  digits.reverse ();
  //declaring a variable to store final expression
  var expression = '';
  //variable to count the number of digits traversed
  var count = 0;
  //for loop to traverse the expression received from user input
  //and set the final expression
  for (let i = 0; i < pattern.length; i++) {
    //if the element is + or - , add them to expression
    if (pattern[i] == '+' || pattern[i] == '-') expression += pattern[i];
    //else add the digit to the expression and increase the count variable
    else {
      expression += digits[count];
      count++;
    }
  }
  //evaluate the final expression using the inbuilt eval() function
  var result = eval (expression);
  // print the final result
  console.log ("Result is: "+result);
  //close the input stream
  readline.close();
});

Screenshot of code for better understanding:

Sample Output:

After reading the input from standard input, we split it using the string.split() function to extract the number and the pattern. Then we extract the individual digits of number in array. After this, we loop through the expression to make our final expression replacing letter with the digits and then evaluate it using the eval function of javascript.