Algorithm

What is an algorithm?

Algorithm is a procedure or step by step process for solving a problem.

• Algorithms can be expressed using different kinds of notations, including pseudocode, flowcharts, programming languages and natural languages.

• Computer algorithm is an instance of logic written in computer software by the programmers.

Let’s learn some of the algorithm. Sample problem definition and algorithm is given below:

1. Problem Definition: Write an algorithm to add given two numbers.

Step 1: Start.

Step 2: Read two numbers A and B.

Step 3: Total = A+B.

Step 4: Display Total.

Step 5: Stop.

Algorithm to C program conversion

 Example of Algorithm to C program conversion.

Problem Definition: Write an algorithm to add given two numbers.

Step 1: Start.

Step 2: Read two numbers A and B.

Step 3: Total = A+B.

Step 4: Display Total.

Step 5: Stop.

#include<stdio.h>
int main()
{
 int A, B, Answer;

 printf("Enter number A:");
 scanf("%d",&A);

 printf("Enter number B:");
 scanf("%d",&B);

 Answer = A + B;
 printf("%d", Answer);
 return 0;
}

Output of program:

Enter number A:5
Enter number B:10
15

2. Problem Definition: Write an algorithm for Subtracting two Numbers.

Step 1: Start.

Step 2: Read two numbers A and B.

Step 3: Answer = A - B.

Step 4: Display SUB.

Step 5: Stop.

Example of Algorithm to C program conversion.

 Example of Algorithm to C program conversion.

Problem Definition: Write an algorithm for Subtracting two Numbers.

Step 1: Start.
Step 2: Read two numbers A and B.
Step 3: Answer = A - B.
Step 4: Display Answer.
Step 5: Stop


#include<stdio.h>
int main()
{
int A, B, Answer;

printf("Enter number A:");
scanf("%d",&A);

printf("Enter number B:");
scanf("%d",&B);

Answer = A - B;
printf("%d", Answer);
 return 0;
}

3. Problem Definition: Write an algorithm to find factorial of a given number.

Step 1: Start

Step 2: Declare variables: N, fact,  i.

Step 3: Initialize variables

            fact = 1

            i = 1

Step 4: Read value of N from user.

Step 5: Repeat following steps until i = N

            fact =  fact * i

            i = i + 1

Step 6: Print fact variable.

Step 7: Stop

C program to find factorial of a given number.

C program to find factorial of a given number. Factorial of number n is defined as follow:

      n! = 1 * 2 * 3 * 4 * ....* n 

#include<stdio.h>
int main()
{
   int i, n;
   double fact=1;
    
printf("Enter number (n): ");
   scanf("%d",&n);

   if (n < 0)
      printf("Factorial is not possible for negative number.");
   else
   {
      for(i=1; i<=n; i++)
      {
          fact = fact * i;     
      }
      printf("Factorial of number %d = %f", n, fact);
   }
}

5. Problem Definition: Write an algorithm for dividing given two numbers.

Step 1: Start.
Step 2: Read two numbers A and B.

Step 3: Answer = A / B.

Step 4: Display Answer.

Step 5: Stop

C programs of known algorithms

Bubble sort algorithm implementation.

#include<stdio.h> int main() {      int i, j, n, temp, data[10];      printf("Enter total numbers to be sorted:");      scanf("%d",&n);      //This program will be able to sort max 10 numbers.           for(i=0; i<n; i++)      {            printf("Enter data[%d]:",i);            scanf("%d",&data[i]);      }      printf("Unsorted data:");      for(i=0; i<n; i++)            printf("%d, ", data[i]);           for(i=0; i<n; i++)      {            for(j=0; j<n-i-1; j++)            {                 if(data[j] > data[j+1])                 {                      temp = data[j];                      data[j] = data[j+1];                      data[j+1] = temp;                 }                                 }      }           printf("\nSorted data:");      for(i=0; i<n; i++)            printf("%d, ", data[i]);      return 0; }

Output of the program:

Enter total numbers to be sorted:5

Enter data[0]:1

Enter data[1]:3

Enter data[2]:2

Enter data[3]:4

Enter data[4]:5

Unsorted data:1, 3, 2, 4, 5,

Sorted data:1, 2, 3, 4, 5,