JavaScript Basics Part- 2

// without function, not reusable:
var inch = 156;
var feet = inch / 12;
console.log(feet); // 13

// with function:
function inchToFeet(inch) {
  var feet = inch / 12;
  return feet;
}

var newFeet = inchToFeet(300);
console.log(newFeet); // 25

// using index of an array:
var inchArr = [156, 288, 300];

var newFeet = inchToFeet(inchArr[1]);
console.log(newFeet); // 24

// using for loop:
var inchArr = [156, 288, 300];

for (i = 0; i < inchArr.length; i++) {
  var feet = inchArr[i] / 12;
  console.log(feet); // 13 24 25
}

// use var or let (mostly) if you want to reassign
let name = "Javed Akhter";
console.log(name.length); /* including space */

if (name.length > 4) {
  name = "Juvu";
}
console.log(name);

// if variable will be fixed or no need to change use const
const country = "Bangladesh";
console.log(country);

const age = 15;
console.log(age);

/* apply const wherever possible */
function inchToFeet(inch) {
  const feet = inch / 12;
  return feet;
}

const newFeet = inchToFeet(300);
console.log(newFeet);

// using index of an array:
const inchArr = [156, 288, 300];

const newFeetArry = inchToFeet(inchArr[1]);
console.log(newFeetArry);

/* divisible by 4 for leap is not always true */
console.log(2030 / 4);
console.log(2032 / 4);

const year = 3996;
const remainder = year % 4;
console.log(remainder);
console.log(remainder == 0);

if (remainder == 0) {
  console.log("The year is a Leap Year");
} else {
  console.log("The year is not a Leap Year");
}

// using function:
function isLeapYear(year) {
  const remainder = year % 4;

  if (remainder == 0) {
    return true;
  } else {
    return false;
  }
}

const checkYear1 = isLeapYear(2016);
console.log(checkYear1);

const checkYear2 = isLeapYear(1700);
console.log(checkYear2); /* not true */

// Method: 1
function isLeapYear(year) {
  if (year % 400 === 0) return true;
  if (year % 100 === 0) return false;
  return year % 4 === 0;
}

console.log(isLeapYear(1700)); // false
console.log(isLeapYear(2016)); // true
console.log(isLeapYear(2000)); // true
console.log(isLeapYear(100)); // false

// Method: 2
// function isLeapYear2(year) {
// return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
// }

function isLeapYear2(year) {
  if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
    return "The year is a leap Year";
  } else {
    return "The Year is not a leap year";
  }
}

console.log(isLeapYear2(1700)); // The Year is not a leap year
console.log(isLeapYear2(2016)); // The year is a leap Year
console.log(isLeapYear2(2000)); // The year is a leap Year
console.log(isLeapYear2(100)); // The Year is not a leap year

// Method 3:
function isLeapYear3(year) {
  return year % 100 === 0 ? year % 400 === 0 : year % 4 === 0;
}

console.log(isLeapYear(1700)); // false
console.log(isLeapYear(2016)); // true
console.log(isLeapYear(2000)); // true
console.log(isLeapYear(100)); // false

/* Factorial e.g. 
4! = 4*3*2*1
10!=1*2*3*4*5*6*7*8*9*10 */

/* assume initial value such that it will not affect the result,
 e.g. for multiply assume initial value 1, for addition 0 */

// iterative method, for loop:
let factorial = 1;
for (let i = 1; i <= 10; i++) {
  factorial = factorial * i;
  console.log(i, factorial);
}

// using function:
function newFactorial(n) {
  let factorial = 1;
  for (let i = 1; i <= n; i++) {
    factorial = factorial * i;
  }
  return factorial;
}

let result = newFactorial(5);
console.log(result); // 120

// 10!=1*2*3*4*5*6*7*8*9*10
// using while loop:
let i = 1;
let factorial = 1;
while (i <= 10) {
  factorial = factorial * i;
  // console.log(i, factorial);
  i++;
}

console.log(factorial); // 3628800

// using function and while:
function newFactorial(n) {
  let i = 1;
  let newFactorial = 1;
  while (i <= n) {
    newFactorial = newFactorial * i;
    i++;
  }
  return newFactorial;
}

let result = newFactorial(6);
console.log(result); // 720

// reverse way:
// 10!=1*2*3*4*5*6*7*8*9*10

// Using For loop:
let factorial1 = 1;
for (let i = 5; i > 1; i--) {
  factorial1 = factorial1 * i;
  console.log(i, factorial1);
}

function factorialize(n) {
  let i = n;
  let newNum = 1;
  for (i; i > 1; i--) {
    newNum *= i; /* newNum = newNum * i */
  }
  return newNum;
}

console.log(factorialize(6)); // 720

// using while:
let i = 5;
let factorial2 = 1;
while (i >= 1) {
  factorial2 = factorial2 * i;
  i--;
}
console.log(factorial2); // 120

function factorialize2(n) {
  let i = n;
  let factorial2 = 1;
  while (i >= 1) {
    factorial2 = factorial2 * i;
    i--;
  }
  return factorial2;
}

console.log(factorialize2(6)); // 720

// Recursive function:

// 10!=1*2*3*4*5*6*7*8*9*10
// 0! = 1
// 2! = 1*2
// 3! = 1*2*3
// 4! = 1*2*3*4
// 5! = 1*2*3*4*5 = 4!*5 = (5-1)! * 5
// n! = (n-1)! * n

function rFactorial(n) {
  if (n == 0) {
    return 1;
  } else {
    return rFactorial(n - 1) * n;
  }
}

let nResult = rFactorial(10);
console.log(nResult); // 3628800

/* 
position 2, 3, 4, 5, n ,i respectively: 
fibo[2] = fibo[2 - 1] + fibo[2 - 2];
fibo[3] = fibo[3 - 1] + fibo[3 - 2];
fibo[4] = fibo[4 - 1] + fibo[4 - 2];
fibo[5] = fibo[5 - 1] + fibo[5 - 2];
fibo[n] = fibo[n - 1] + fibo[n - 2];
fibo[i] = fibo[i - 1] + fibo[i - 2]; */

// using For loop:
let fibo = [0, 1];

for (let i = 2; i <= 12; i++) {
  fibo[i] = fibo[i - 1] + fibo[i - 2];
  // console.log(fibo[i], fibo[i - 1], fibo[i - 2])
}

console.log(fibo);
// [ 0,  1,  1,  2,  3,  5, 8, 13, 21, 34, 55, 89, 144 ]

// using function:
function fibonacci(n) {
  let fibo = [0, 1];

  for (let i = 2; i <= n; i++) {
    fibo[i] = fibo[i - 1] + fibo[i - 2];
  }
  return fibo;
}

let fiboResult = fibonacci(12);
console.log(fiboResult);
// [ 0,  1,  1,  2,  3,  5, 8, 13, 21, 34, 55, 89, 144 ]

function rFibonacci(n) {
  if (n == 0) {
    return 0;
  }
  if (n == 1) {
    return 1;
  } else {
    return rFibonacci(n - 1) + rFibonacci(n - 2);
  }
}

let rResult = rFibonacci(10);
console.log(rResult); // 55

// [0 , 1, 1, 2, 3, 5, 8,, 13, 21,]

function sFibonacci(n) {
  if (n == 0) {
    return [0];
  } else if (n == 1) {
    return [0, 1];
  } else {
    // find array with nth item
    let fibo = sFibonacci(n - 1);
    let nextItem = fibo[n - 1] + fibo[n - 2];
    fibo.push(nextItem);
    return fibo;
  }
}

let sResult1 = sFibonacci(1);
let sResult2 = sFibonacci(2);
let sResult3 = sFibonacci(3);
let sResult4 = sFibonacci(4);
let sResult8 = sFibonacci(10);
console.log(sResult1); // [ 0, 1 ]
console.log(sResult2); // [ 0, 1, 1 ]
console.log(sResult3); // [ 0, 1, 1, 2 ]
console.log(sResult4); // [ 0, 1, 1, 2, 3 ]
console.log(sResult8); // [ 0, 1,  1,  2,  3, 5, 8, 13, 21, 34, 55]

function isPrime(n) {
  for (i = 2; i < n; i++) {
    // console.log(i, n % i);
    if (n % i == 0) {
      return "Not a Prime Number";
    }
  }
  return "The number is a Prime number";
}

let pResult1 = isPrime(128);
let pResult2 = isPrime(79);

console.log(pResult1); // Not a Prime Number
console.log(pResult2); // The number is a Prime number

let a = 5;
let b = 7;
console.log("Before swap: a=", a, ", b=", b);
// Before swap: a= 5 , b= 7

// Swap using a temporary variable:
let temp = a; /* store a value in temp variable */
a = b; /* overwrite a value with a value */
b = temp; /* overwrite b value with temp value */

console.log("After swap: a=", a, ", b=", b);
// After swap: a= 7 , b= 5

// Swap using addition and difference:
let x = 5;
let y = 7;
console.log("Before swap: x=", x, ", y=", y);
// Before swap: x= 5 , y= 7

x = x + y;
/* add current x and current y so that we can get combined 
value of x and y (in this case 12) and store it in new x */
y = x - y; /* now new y equal the new x minus y, which is 12-7= 5 */
x = x - y; /* now to transfer y value, overwrite new x, 12-5= 7  */

console.log("After swap: x=", x, ", y=", y);
// After swap: x= 7 , y= 5

// Swap using destructing assignment:
let p = 5;
let q = 7;
console.log("Before swap: p=", p, ", q=", q);
// Before swap: p= 5 , q= 7
[p, q] = [q, p];
/* a temporary array [q, p] is created, which evaluates to [7,5] */
console.log("After swap: p=", p, ", q=", q);
// After swap: p= 7 , q= 5

let num = 2.12458;

// the Math.floor() function returns the largest integer less than or equal to a given number.
let result1 = Math.floor(num);
console.log(result1); // 2

// the Math.ceil() function always rounds a number up to the next largest integer.
let result2 = Math.ceil(num);
console.log(result2); // 3

// the Math.round() function returns the value of a number rounded to the nearest integer.
let result3 = Math.round(num);
console.log(result3); // 2

// random number 0 t0 10:
let dice = Math.random() * 6; /* with decimal */
console.log(dice); // example: 1.2463552614334286

let output = Math.round(dice); /* without decimal */
console.log(output); // example: 1

for (i = 0; i < 10; i++) {
  let dice = Math.random() * 6;
  let output = Math.round(dice);
  console.log("For Loop: ", output);
}

let business = 450;
let minister = 350;
let sochib = 750;

// if compare business and minister only:
if (business > minister) {
  console.log("Business is bigger"); // output
} else {
  console.log("Minister is bigger");
}

// if compare business, minister sochib:
if (business > minister) {
  if (business > sochib) {
    console.log("Business is bigger");
  } else {
    console.log("Sochib is bigger");
  }
} else {
  if (minister > sochib) {
    console.log("Minister is bigger");
  } else {
    console.log("sochib is bigger");
  }
}
// output: sochib is bigger

// the Math.max() function returns the largest of the zero or more numbers given as input

let max = Math.max(business, minister, sochib);
console.log(max); // 750
// output: 750

console.log(Math.max(1, 3, 2));
// output: 3

console.log(Math.max(-1, -3, -2));
// output: -1

const array1 = [1, 3, 2];

console.log(Math.max(...array1));
// output: 3

const marks = [45, 81, 63, 98, 56, 35, 23];
let max = marks[0];

for (let i = 0; i < marks.length; i++) {
  // debugger;
  let element = marks[i];
  if (element > max) {
    max = element;
  }
}

console.log("Highest value is: ", max);
// Highest value is:  98

let numbers = [45, 65, 68, 12, 3, 54, 65];

let sum = 0;
for (let i = 0; i < numbers.length; i++) {
  let element = numbers[i];
  sum = sum + element;
}

console.log("Total of the numbers: ", sum);
// Total of the numbers:  312

// using function:
function getArrSum(arrayNumbers) {
  let sum = 0;
  for (let i = 0; i < arrayNumbers.length; i++) {
    let element = arrayNumbers[i];
    sum = sum + element;
  }
  return sum;
}

let num = [45, 65, 68, 12, 3];
let getArrSumResult = getArrSum(num);

console.log("Total: ", getArrSumResult); // Total:  193
console.log("Total: ", getArrSum([50, 100, 20, 10])); // Total:  180

let arrNum = [3, 6, 2, 7, 3, 2, 8, 1, 9, 11, 56];

let uniqueNum = [];
for (let i = 0; i < arrNum.length; i++) {
  let element = arrNum[i]; /* each index element */
  let index =
    uniqueNum.indexOf(element); /* check the element index in uniqueNum */

  if (index == -1) {
    /* when the element is not found in uniqueNum, push will add */
    uniqueNum.push(element);
  }
}
console.log(uniqueNum);
// [ 3, 6,  2,  7, 8, 1, 9, 11, 56 ]

// using function:
function findUnique(arrayX) {
  let uniqueNum = [];
  for (let i = 0; i < arrayX.length; i++) {
    let element = arrayX[i];
    let index = uniqueNum.indexOf(element);

    if (index == -1) {
      uniqueNum.push(element);
    }
  }
  return uniqueNum;
}

console.log(findUnique([5, 5, 7, 9, 0, 5, 9, 0, 3]));
// [ 5, 7, 9, 0, 3 ]

let speech = "I am a good person. I don't snore at night";
// console.log(speech.length);
// console.log(speech[3]);

// Target spaces between words
let count = 0;
for (let i = 0; i < speech.length; i++) {
  let char = speech[i];
  // console.log(char);

  if (char == " " && speech[i - 1] != " ") {
    /* speech[i - 1] is applied to ignor double spaces */
    count++;
    /* 1 less than expected word count cause there is no space after last word */
  }
}
count++; /* add 1 to fix the prior count */

console.log(count); // 10

function reverseString(str) {
  let reverse = "";
  for (let i = 0; i < str.length; i++) {
    let char = str[i];
    reverse = char + reverse; /* put char in the beginning to reverse */
  }
  return reverse;
}

let statement = "Hello Alien, How are you doing?";
let reverseStrOut = reverseString(statement);
console.log(reverseStrOut);
// ?gniod uoy era woH ,neilA olleH

// Write an function to find largest value.
function largestNumber(numbers) {
  var larger = numbers[0];
  for (var i = 0; i < numbers.length; i++) {
    var element = numbers[i];
    if (element > larger) {
      larger = element;
    }
  }
  return larger;
}

console.log(largestNumber([45, 78, 89, 23])); // 89

// Find factorial using iteration
// 5!=5*4*3*2*1
function factorial(num) {
  var fact = 1;
  for (var i = 1; i <= num; i++) {
    fact = fact * i;
  }
  return fact;
}

console.log(factorial(5)); // 120

// Write a recursive function to find factorial.
function rFactorial(num) {
  if (num == 1) {
    return 1;
  } else {
    return num * rFactorial(num - 1);
  }
}

console.log(rFactorial(5)); // 120

/* assume you went to amazon forest, the more deeper you will go inside the forest, 
the chance of seeing more animals is greater. 
Let's assume from the beginning of the forest to first 10 miles, you had saw 50 animals,
then second 10 miles 100 animals, and third 10 miles or greater 300 animals respectively. 
Write a function named animalCalculator to find the totalanimal for a given input of depth. */

var depth = 12;

function animalCalculator(depth) {
  var animal = 0;

  if (depth <= 10) {
    animal = depth * 5;
  } else if (depth <= 20) {
    var firstPart = 10 * 50;
    var remaining = depth - 10;
    var secondPart = remaining * 100;
    animal = firstPart + secondPart;
  } else {
    var firstPart = 10 * 50;
    var secondPart = 10 * 100;
    var remaining = depth - 20;
    var thirdPart = remaining * 300;
    animal = firstPart + secondPart + thirdPart;
  }
  return animal;
}

console.log(animalCalculator(32)); // 5100