Python range function recursive


Recursion:
  • The process of calling a function by itself is called recursion and the function which calls itself is called recursive function.
  • Recursion is used to solve various mathematical problems by dividing it into smaller problems. This method of solving a problem is called Divide and Conquer. In programming, it is used to divide complex problem into simpler ones and solving them individually.
  • In order to prevent infinite recursive call,we need to define proper exit condition in a recursive function.



  • Python program to show recursive function

    • n=4
    • def  a(n):
    •  if n==0:
    •     return 0
    •  else:
    • print(n)
    • Return a(n-1)


    • Python range for float numbers
    • Limitation of  python’s range() function
    • The main limitation of Python’s range() is it works only with integers. Python range() doesn’t support the float type i.e., we cannot use floating-point or non-integer number in any of its argument.
    • For example,  Let’s see the following source code
    • for num in range(0, 5.5, 0.1):
    •   print (num)
    • If you try to execute above code Python will raise a TypeError: ‘float’ object cannot be interpreted as an integer.


    • Now, Let see how to generate the range for float numbers? There are various ways to do this Let see one by one with the examples.
    • Use numpy’s arange() function to generate the range for float numbers in Python.
    • We can use the numpy module of Python programming language to get the range of floating-point numbers.

    • NumPy library has various numeric functions and mathematical functions to operate on multi-dimensional arrays and matrices.
    • NumPy has the arange() function to get the range of a floating-point number.
    • arange() function has the same syntax and functionality as python range() function.
    • Additionally, it also supports floating-point numbers in any of its argument.
    • i.e., we can pass float number in the start, stop and step arguments.

    Syntax of numpy’s arange() function: –
    • arange (start, stop, step)
    • Let demonstrate the use with the following example.































    Else statement in python with example program

    Else Statement in Python:


    • The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false. Here comes the else statement.
    • We can use the else statement with if statement to execute a block of code when the condition is false

    if (condition):

        # Executes this block if

        # condition is true

    else:

        # Executes this block if

        # condition is false


    #1: Python program to illustrate If else statement
    1.  i = 2;
    2. if i< 1:
    3.     print ("i is smaller than 1")
    4.     print ("i'm in if Block")
    5. else:
    6.     print ("i is greater than 1")
    7.     print ("i'm in else Block")
    8. print ("i'm not in if and not in else Block")

    Output:
    1. I is greater than 1
    2. I'm in else Block
    3. I'm not in if and not in else Block



    Fibonacci series in c without recursion

    • In Fibonacci series the first two numbers in the Fibonacci sequence are 0 and 1 and each subsequent number is the sum of the previous two. For example Fibonacci series is 0, 1, 1, 2, 3, 5, 8,13, 21
    • C Program to Display Fibonacci Sequence 
    • Fibonacci series means next number will be generated as sum of previous two numbers.

    #1: C example program on Fibonacci series

    1. #include <stdio.h>

    2. void main()
    3. {
    4.     int  fib1 = 0, fib2 = 1, fib3, limit, count = 0;

    5.     printf("Enter the limit to generate the Fibonacci Series \n");
    6.     scanf("%d", &limit);
    7.     printf("Fibonacci Series is ...\n");
    8.     printf("%d\n", fib1);
    9.     printf("%d\n", fib2);
    10.     count = 2;
    11.     while (count < limit)
    12.     {
    13.         fib3 = fib1 + fib2;
    14.         count++;
    15.         printf("%d\n", fib3);
    16.         fib1 = fib2;
    17.         fib2 = fib3;
    18.     }
    19. }
    Output:
    1. Enter the limit to generate the Fibonacci Series
    2. 20
    3. Fibonacci Series is ...
    4. 0
    5. 1
    6. 1
    7. 2
    8. 3
    9. 5
    10. 8
    11. 13
    12. 21
    13. 34
    14. 55
    15. 89
    16. 144
    17. 233
    18. 377
    19. 610
    20. 987
    21. 1597
    22. 2584
    23. 4181


    If statement in python example program

    Decision Making In Python (IF):


    • As we lead our life we have to take decisions. Similarly, as we make progress in programming and try to implement complicated logics, our program has to take decisions. But how? Well the answer is below
    • if statement
    • If statement is the most simple decision making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.


     If condition:
    Statement 1
    Statement 2
    Statement 3
    ………………..
    …………………
    ………………..
    Statement n

    • Here the condition is evaluated in terms of boolean values i.e. either the evaluation of condition results 1 or 0 i.e.. True(1) or False(0) 
    • If the condition evaluates to True(1) then the block of statements below the if statement gets executed 



    #1: Python example program to illustrate if statement

    1. #Python program to illustrate if statement
    2. a=21
    3. If a<21:
    4. print(“if-1 statement is executed successfully”)
    5. If a>18:
    6. print(“if-2 statement is executed successfully”)

    7. Output:
    8. if-2 statement is executed successfully

    Output:
    1. if-2 statement is executed successfully


    Prime number program in c using for loop

    Prime number program in C
    • A prime number is a whole number greater than 1 whose only factors are 1 and itself. A factor is a whole number that can be divided evenly into another number. The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29. 
    • Numbers that have more than two factors are called composite numbers.

    #1:  Prime number program in c using for loop
    1. #include <stdio.h>
    2. void main()
    3. {
    4.   int n1, n2,j, flag;
    5.   long int  i;
    6.   printf("Enter First  numbers(intevals): ");
    7.   scanf("%d", &n1);
    8.   printf("Enter Second  numbers(intevals): ");
    9.   scanf("%d", &n2);
    10.   printf("Prime numbers between %d and %d are: ", n1, n2);
    11.   for(i=n1+1; i<n2; ++i)
    12.   {
    13.       flag=0;
    14.       for(j=2; j<=i/2; ++j)
    15.       {
    16.         if(i%j==0)
    17.         {
    18.           flag=1;
    19.           break;
    20.         }
    21.       }
    22.       if(flag==0)
    23.         printf("%ld ",i);
    24.   }
    25. }


    Output:
    1. Enter First  numbers(intevals): 1
    2. Enter Second  numbers(intevals): 500
    3. Prime numbers between 1 and 500 are: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67
    4. 71 73 79 83 89 97 101 103 107
    5. 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229
    6. 233 239 241 251 257 263 269 271
    7. 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 383 389 397 401 409
    8. 419 421 431 433 439 443 449 457
    9. 461 463 467 479 487 491 499
    10. Process returned 500 (0x1F4)   execution time : 4.833 s
    11. Press any key to continue.


    prime numbers program


    Switch case in c example program

    • switch case in c programming questions
    • switch case with do you want to continue in c
    • A switch case is a control statement in C that allows you to choose between several different options based on the value of a particular expression. 
    • C has a built-in multi-way decision statement known as a switch. It is a keyword we can select a single option from multiple options. The switch  is having expression; each and every option is known as case and must be followed by colon.
    • Each and every case ends with break statement.
    • The last case is default even that will have break.
    •  The break is a keyword. Each and every case ends with break statement

     SYNTAX:-

     switch(expression)
     {
        case value-1 :block-1 break;
        case value-2 :block-2 break;
        case value-3 :block-3 break;
        .........
        .........
        .........
        .........
        default :default-block break;
     }

    Here is an example of how to use a switch case in a C program:

    #1; switch case in c programming questions

    1. # include <stdio.h>
    2. void main() {
    3.     char operator;
    4.     double a,b;
    5.     printf("Enter an operator (+, -, *,): ");
    6.     scanf("%c", &operator);
    7.     printf("Enter two numbers ");
    8.     scanf("%lf %lf",&a, &b);
    9.     switch(operator)
    10.     {
    11.         case '+':
    12.             printf("%.1lf + %.1lf = %.1lf",a, b, a + b);
    13.             break;
    14.         case '-':
    15.             printf("%.1lf - %.1lf = %.1lf",a, b, a - b);
    16.             break;
    17.         case '*':
    18.             printf("%.1lf * %.1lf = %.1lf",a, b, a * b);
    19.             break;
    20.         case '/':
    21.             printf("%.1lf / %.1lf = %.1lf",a, b, a / b);
    22.             break;
    23.         default:
    24.             printf("Error! operator is not correct");
    25.     }
    26. }

    Output:
    1. Enter an operator (+, -, *,): +
    2. Enter two numbers 12
    3. 12
    4. 12.0 + 12.0 = 24.0
    5. Process returned 18 (0x12)   execution time : 7.392 s
    6. Press any key to continue.



    • In the below  example, the program prompts the user to enter a number and then uses a switch case to determine what to do based on the value of the number. If the user enters 1, the program will print "You entered 1.
    • " If the user enters 2, the program will print "You entered 2," and so on. If the user enters a value that is not covered by any of the cases, the default case will be executed.



    Python program to find factorial without recursion

    The factorial of a positive integer n is the product of all positive integers less than or equal to n. The factorial of a number is represented by the symbol "!" . For example, the factorial of 5 is 5 * 4 * 3 * 2 * 1 = 120.

    Here is a Python function that calculates the factorial of a given number using a for loop:

    def factorial(n):
        if n < 0:
            return None
        if n == 0:
            return 1
        result = 1
        for i in range(1, n+1):
            result *= i
        return result

    This function takes a single argument, n, and returns the factorial of n. It first checks if n is less than 0, if so it returns None. If n is equal to 0, it returns 1 (since the factorial of 0 is defined to be 1). It then initializes a variable named result to 1, then uses a for loop to iterate over the range of integers from 1 to n inclusive and multiply each number to result variable. Finally, the function returns the value of result, which is the factorial of n.

    You can call this function and pass in any positive integer to calculate its factorial:

    >>> factorial(5)
    120
    >>> factorial(3)
    6
    >>> factorial(10)
    3628800

    Alternatively python has math.factorial function which you can use without writing your own function.

    import math
    math.factorial(5)

    Do note that factorial of number can be very large, even for relatively small numbers and python integers may not be large enough to store those values.

    #1: Python program to find factorial of a given number without using recursion

    1. #Factorial without recursion

    2. n=int(input("Enter the number: "))
    3. fact=1
    4. if n<0:
    5.     print("factorial doesn't exist for negative numbers")
    6. else:
    7.     for i in range(1,n+1):
    8.         fact=fact*i
    9.     print("factorial of", n, "is", fact)

    Output:

    1. Enter the number: 5
    2. factorial of 5 is 120





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    Find factorial of a number by using recursion using python

    • Python program to find factorial of a number using recursion in python.
    • Algorithm to find factorial of a number using recursion function using python.

    #1: Python program to find factorial of a given number using recursion

    1. #Factorial using recursion
    2. def fact(n):
    3.     if n==1:
    4.         return 1
    5.     else:
    6.         return n*fact(n-1)

    7. n=int(input("Enter the number: "))
    8. result=fact(n)
    9. print("Factorial of",n,"is", result)

    Output:

    1. Enter the number: 6
    2. Factorial of 6 is 720



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    Java program to check valid Balanced parentheses

    Balanced parentheses:
    •   A string which contains below characters in correct order.
    •  "{}" "[]" "()"
    • We need to check whether given string has valid order of parenthesis order.
    • If the parenthesis characters are placed in order then we can say its valid parentheses or balanced parentheses.
    • If the parentheses characters are not in correct order or open and close then we can say it is not balanced or invalid parenthesis.
    • Program to check given string has a valid parenthesis or not.

    #1: Java example program to check given string has valid parenthesis or not.


    1. package instanceofjava;

    2. import java.util.Stack;

    3. public class BalancedParenthensies {

    4. public static void main(String[] args) {
    5. System.out.println(checkParenthensies("{(xxx,yyy)}"));
    6. System.out.println(checkParenthensies("{)(acd,bcvfs}"));
    7. System.out.println(checkParenthensies("{(xxx},yyy)"));
    8. System.out.println(checkParenthensies("[(xxx),yyy]"));
    9. }
    10. public static boolean checkParenthensies(String str) {
    11.         Stack<Character> object  = new Stack<Character>();
    12.         for(int i = 0; i < str.length(); i++) {
    13.             char ch = str.charAt(i);
    14.             if(ch == '[' || ch == '(' || ch == '{' ) {     
    15.             object.push(ch);
    16.             } else if(ch == ']') {
    17.                 if(object.isEmpty() || object.pop() != '[') {
    18.                     return false;
    19.                 }
    20.             } else if(ch == ')') {
    21.                 if(object.isEmpty() || object.pop() != '(') {
    22.                     return false;
    23.                 }           
    24.             } else if(ch == '}') {
    25.                 if(object.isEmpty() || object.pop() != '{') {
    26.                     return false;
    27.                 }
    28.             }
    29.         }
    30.         return object.isEmpty();
    31.     }
    32. }

    Output:
    1. true
    2. false
    3. false
    4. true

    check valid java balanced parenthesis


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