C Programming Language || Hands On Coding

#CProgramming #SpyNumber #NumberTheory

Check Spy Number

#include <stdio.h>
#include <stdbool.h>

bool isSpyNumber(int num) {
    int sum = 0;
    int product = 1;
    int temp = num;

    while (temp > 0) {
        int digit = temp % 10;
        sum += digit;
        product *= digit;
        temp /= 10;
    }

    return sum == product;
}

int main() {
    int number;
    scanf("%d", &number);

    if (isSpyNumber(number)) {
        printf("Spy Number");
    } else {
        printf("Not Spy Number");
    }

    return 0;
}

#CProgramming #MagicNumber #Algorithm

Check if a Number is a Magic Number

#include <stdio.h>

int sum_digits(int n) {
    int sum = 0;
    while (n > 0) {
        sum += n % 10;
        n /= 10;
    }
    return sum;
}

int is_magic(int n) {
    while (n > 9) {
        n = sum_digits(n);
    }
    return (n == 1);
}

int main() {
    int num;
    scanf("%d", &num);
    if (is_magic(num)) {
        printf("Magic Number\n");
    } else {
        printf("Not a Magic Number\n");
    }
    return 0;
}

#CProgramming #NeonNumber #Algorithm

Check Neon Number

#include <stdio.h>

int main() {
  int n, square, sum = 0, temp;

  scanf("%d", &n);

  square = n * n;
  temp = square;

  while (temp > 0) {
    sum += temp % 10;
    temp /= 10;
  }

  if (sum == n) {
    printf("Neon");
  } else {
    printf("Not Neon");
  }

  return 0;
}

#CProgramming #AutomorphicNumber #InterviewQuestion

Check Automorphic Number

#include <stdio.h>
#include <stdbool.h>

int main() {
 int num, sq;
 printf("Enter a number: ");
 scanf("%d", &num);
 sq = num * num;
 int temp = num;
 int digits = 0;
 while (temp > 0) {
 digits++;
 temp /= 10;
 }
 int lastDigits = sq % (int)pow(10, digits);
 if (lastDigits == num) {
 printf("%d is an Automorphic number.\n", num);
 } else {
 printf("%d is not an Automorphic number.\n", num);
 }
 return 0;
}

#CProgramming #Divisors #Algorithms

Print All Divisors of a Number

#include <stdio.h>

void printDivisors(int n) {
  for (int i = 1; i <= n; i++) {
    if (n % i == 0) {
      printf("%d ", i);
    }
  }
  printf("\n");
}

int main() {
  int num;
  scanf("%d", &num);
  printDivisors(num);
  return 0;
}

#CProgramming #Factorial #BigNumbers

Find Factorial (Big Numbers using Arrays)

#include <stdio.h>

int multiply(int x, int res[], int res_size) {
    int carry = 0;
    for (int i = 0; i < res_size; i++) {
        int prod = res[i] * x + carry;
        res[i] = prod % 10;
        carry = prod / 10;
    }
    while (carry) {
        res[res_size] = carry % 10;
        carry = carry / 10;
        res_size++;
    }
    return res_size;
}

void factorial(int n) {
    int res[500];
    res[0] = 1;
    int res_size = 1;

    for (int x = 2; x <= n; x++)
        res_size = multiply(x, res, res_size);

    for (int i = res_size - 1; i >= 0; i--)
        printf("%d", res[i]);
    printf("\n");
}

int main() {
    int n = 100;
    factorial(n);
    return 0;
}

#CProgramming #HarshadNumber #InterviewCode

Check Harshad (Niven) Number

#include <stdio.h>
#include <stdbool.h>

bool isHarshad(int n) {
    int sum = 0;
    int temp = n;
    while (temp > 0) {
        sum += temp % 10;
        temp /= 10;
    }
    return (n % sum == 0 && sum != 0);
}

int main() {
    int num;
    scanf("%d", &num);
    if (isHarshad(num)) {
        printf("Harshad\n");
    } else {
        printf("Not Harshad\n");
    }
    return 0;
}

#CProgramming #Summation #InterviewPrep

Sum of First N Natural Numbers

#include <stdio.h>

int sum_n(int n) {
  if (n <= 0) {
    return 0;
  }
  return n * (n + 1) / 2;
}

int main() {
  int num = 10;
  int sum = sum_n(num);
  printf("Sum of first %d natural numbers: %d\n", num, sum);
  return 0;
}

#CProgramming #Algorithm #DigitalRoot

Digital Root of a Number

#include <stdio.h>

int digitalRoot(int n) {
 while (n >= 10) {
 int sum = 0;
 while (n > 0) {
 sum += n % 10;
 n /= 10;
 }
 n = sum;
 }
 return n;
}

int main() {
 int num = 12345;
 printf("Digital root of %d is %d\n", num, digitalRoot(num));
 return 0;
}

#CProgramming #Recursion #Iteration

Sum of Digits (Recursive and Iterative)

#include <stdio.h>

int sumDigitsIterative(int n) {
    int sum = 0;
    while (n > 0) {
        sum += n % 10;
        n /= 10;
    }
    return sum;
}

int sumDigitsRecursive(int n) {
    if (n == 0) {
        return 0;
    }
    return (n % 10) + sumDigitsRecursive(n / 10);
}

int main() {
    int num = 12345;
    printf("Iterative Sum of Digits: %d\n", sumDigitsIterative(num));
    printf("Recursive Sum of Digits: %d\n", sumDigitsRecursive(num));
    return 0;
}