Deep dive into some tricky programming problems

1. Find the largest element in an array

var arr = [10, 20, 30, 40, 50];
var max = arr[0];
for(var i=0; i < arr.length; i++) {
  var a = arr[i];
  if(a > max){
    max = a;
  }
}
console.log(“Largest in the array: “, max);

2. Sum of all the elements in an array

var arr = [10, 20, 30, 40, 50];
var sum = 0;
for(var i=0; i < arr.length; i++) {
  var a = arr[i];
  sum += a;
}
console.log(“Sum of the elements in the array: “, sum);

3. Remove duplicate items from an array

var arr = [10, 20, 30, 20, 40, 30, 50];
var final = [];
for(var i=0; i < arr.length; i++) {
  var a = arr[i];
  var index = final.indexOf(a);
  if(index == -1) {
    final.push(a);
  }
}
console.log(“Final array after removing duplicates: “, final);

4. Count the number of words in a string

var str = “Hello World”;
var totalWords = 0;
for(var i=0; i<str.length; i++) {
  var a = str[i];
  if(a == “ “ && str[i-1] != “ “){
    totalWords++;
  }
}
totalWords ++;
console.log(“Total words in the string: “, totalWords);

5. Reverse a string

var str = “Hello World”;
var rev = “”;
for(var i=0; i<str.length; i++) {
  var char = str[i];
  rev = char + rev;
}
console.log(“Reversed string: “, rev);

6. Calculate Factorial of a number using for loop

function factorization(num) {
  var factorial = 1;
  for(var i=1; i <= num; i++){
    factorial = factorial * i;
    }
  return factorial;
}
var result = factorization(10);
console.log("Factorial value of the number: ", result);

7. Calculate Factorial of a number using a while loop

function factorization(num) {
  var factorial = 1;
  var i = 1;
  while(i <= num) {
    factorial = factorial * i;
    i++;
    }
  return factorial;
}
var result = factorization(10);
console.log("Factorial value of the number: ", result);

8. Calculate Factorial in a Recursive function

function factorization(number) {
  if(number == 0){
    return 1;
  }
  else{
    return number * factorization(number -1);
  }
}
var result = factorization(10);
console.log(“Factorial value of the number: “, result);

9. Create a Fibonacci Series using a for loop

function fibonacci(n) {
  var fib = [0, 1];
  for(var i=2; i <= n; i++){
    fib[i] = fib[i-1] + fib[i-2];
    }
    return fib;
}
var result = fibonacci(10);
console.log(“Fibonacci series: “, result);

10. Create Fibonacci series in a Recursive way

function fibonacci(n) {
  if(n == 0){
    return [0];
  }
  else if(n == 1){
    return [0, 1];
  }
  else{
    var fib = fibonacci(n-1);
    var next = fib[n - 1] + fib[n - 2];
    fib.push(next);
    return fib;
  }
}
var result = fibonacci(10);
console.log("Fibonacci series: ", result);

11. Fibonacci Element in a Recursive Way

function fibonacci(n) {
if(n == 0){
return 0;
}
if(n == 1){
return 1;
}
else{
return fibonacci(n - 1) + fibonacci(n - 2);
}
}
var result = fibonacci(10);
console.log(result);

12. Check whether a number is a Prime Number or Not

function isPrime(n){
  for(var i=2; i < n; i++){
    if(n % i == 0){
      return “Not a prime number”;
    }
  }
  return “Prime number”;
}
var result = isPrime(23);
console.log(result);