Algorithm my understanding

In computer programming, algorithm are the set of well defined instruction in sequence to solve a program. An algorithm should always have a clear stopping point.


Qualities of a good algorithm
•Precision – the steps are precisely stated(defined).
•Uniqueness – results of each step are uniquely definedand only depend on the input and the result of the precedingsteps.
•Finiteness – the algorithm stops after a finite number ofinstructions are executed.
•Input – the algorithm receives input.
•Output – the algorithm produces output.
•Generality – the algorithm applies to a set ofinputs.


Eg: Google Maps, Define from and to positions and click get directions, clear steps will be provided.


In Simple terms
1.Inputs and outputs should be defined precisely.
2.Each steps in algorithm should be clear and unambiguous.
3.Algorithm should be most effective among many different ways to solve a problem.
4.An algorithm shouldn't have computer code. Instead, the algorithm should be written in such a way that, it can be used in similar programming languages.
Every algorithm should have the following five characteristics:
1. Input
2. Output
3. Definiteness
4. Effectiveness
5. Termination

Examples Of Algorithms In Programming


Write an algorithm to add two numbers entered by user.
Step 1: Start
Step 2: Declare variables num1, num2 and sum.
Step 3: Read values num1 and num2.
Step 4: Add num1 and num2 and assign the result to sum.
        sum←num1+num2
Step 5: Display sum
Step 6: Stop


Write an algorithm to find the largest among three different numbers entered by user.
Step 1: Start
Step 2: Declare variables a,b and c.
Step 3: Read variables a,b and c.
Step 4: If a>b
           If a>c
              Display a is the largest number.
           Else
              Display c is the largest number.
        Else
           If b>c
              Display b is the largest number.
           Else
              Display c is the greatest number. 
Step 5: Stop


Write an algorithm to find the factorial of a number entered by user.
Step 1: Start
Step 2: Declare variables n,factorial and i.
Step 3: Initialize variables
          factorial←1
          i←1
Step 4: Read value of n
Step 5: Repeat the steps until i=n
     5.1: factorial←factorial*i
     5.2: i←i+1
Step 6: Display factorial
Step 7: Stop


Write an algorithm to check whether a number entered by user is prime or not.
Step 1: Start
Step 2: Declare variables n,i,flag.
Step 3: Initialize variables
        flag←1
        i←2 
Step 4: Read n from user.
Step 5: Repeat the steps until i<(n/2)
     5.1 If remainder of n÷i equals 0
            flag←0
            Go to step 6
     5.2 i←i+1
Step 6: If flag=0
           Display n is not prime
        else
           Display n is prime
Step 7: Stop


Write an algorithm to find the Fibonacci series till term≤1000.
Step 1: Start
Step 2: Declare variables first_term,second_term and temp.
Step 3: Initialize variables first_term←0 second_term←1
Step 4: Display first_term and second_term
Step 5: Repeat the steps until second_term≤1000
     5.1: temp←second_term
     5.2: second_term←second_term+first term
     5.3: first_term←temp
     5.4: Display second_term
Step 6: Stop


Write an algorithm for a for loop.
for (/*EXPRESSION 1*/;/*EXPRESSION 2*/;/*EXPRESSION 3*/) {
 /*STATEMENT 4*/
 }
would be:
1.EXPRESSION 1
2.If EXPRESSION 2 is false go to step 6
3.STATEMENT 4
4.EXPRESSION 3
5.Go to step 2
6.End

https://en.wikipedia.org/wiki/Algorithm