Python Puzzle Remove even numbers

Python Puzzle Remove even numbers

# Wrong approach (incorrect - using For loop)

def removeEven(List):

    print(id(List)) # 139909029905664

    for each in List:

       i f each % 2 == 0:

          List.remove(each)

myList = [152, 168, 154, 32, -55, 81, 146, -34, -124, -9, 4, -31, -131, -86, -190, -38]

print(id(myList)) # 139909029905664

print(myList) # [1, 2, 4, 5, 10, 6, 3]

removeEven(myList)

print(myList) # [168, 32, -55, 81, -34, -9, -31, -131, -190]

# Wrong as when element gets deleted, index goes down

print('-' * 60)

# Correct approach (using While loop)

def removeEvenNew(List):

    print(id(List))

    i = 0

    while i < len(List):

      if List[i] % 2 == 0:

          List.remove(List[i])

      else:

          i += 1 

myList = [152, 168, 154, 32, -55, 81, 146, -34, -124, -9, 4, -31, -131, -86, -190, -38]

print(id(myList))

print(myList) # 

removeEvenNew(myList)

print(myList) # [-55, 81, -9, -31, -131]

Output:

140407115793920

[152, 168, 154, 32, -55, 81, 146, -34, -124, -9, 4, -31, -131, -86, -190, -38]

140407115793920

[168, 32, -55, 81, -34, -9, -31, -131, -190]

------------------------------------------------------------

140407114861888

[152, 168, 154, 32, -55, 81, 146, -34, -124, -9, 4, -31, -131, -86, -190, -38]

140407114861888

[-55, 81, -9, -31, -131]

Learning control flow statements in Python

#!/usr/local/bin/python2.7

'''
    #Learning control flow statements in Python
    File name: python_control_flow_statements.py
    Author: Prabhath Kota
    Date: June 29, 2018
    Python Version: 2.7
'''

'''
Sequential
Selection (Python Conditional Statements) 
if
if...else
if..elif..else statements
nested if statements
not operator in if statement
and operator in if statement
in operator in if statement
Repetetion
for loop
while loop
'''

print('-------------------Python if statements----------------')
x=20
y=10
if x > y :
  print("X is bigger")
#X is bigger

print('-------------------Python if...else statements----------------')
x=10
y=20
if x > y :
  print("X is bigger")
else :
  print("Y is bigger")
#Y is bigger

print('-------------------Python if...else...else statements----------------') 
x=500
if x > 500 :
  print("X is greater than 500")
elif x < 500 :
  print("X is less than 500")
elif x == 500 :
  print("X is 500")
else :
  print("X is not a number")
#X is 500

print('-------------------Python Nested if statements----------------') 
mark = 72
if mark > 50:
  if mark >= 80:
    print ("You got A Grade !!")
  elif mark >= 60 and mark < 80 :
    print ("You got B Grade !!")
  else:
    print ("You got C Grade !!")
else:
  print("You failed!!")
#You got B Grade !!

print('-------------------not operator in if statement----------------') 
mark = 100
if mark != 100: #mark != 100
  print("mark is not 100")
else:
  print("mark is 100")
#mark is 100

print('-------------------and operator in if statement----------------') 
mark = 72
if mark > 80:
  print ("You got A Grade !!")
elif mark >= 60 and mark < 80 :
  print ("You got B Grade !!")
elif mark >= 50 and mark < 60 :
  print ("You got C Grade !!")
else:
  print("You failed!!")
#You got B Grade !!

print('-------------------in operator in if statement----------------') 
color = ['Red','Blue','Green']
selColor = "Red"
if selColor in color:
  print("Red is in the list")
else:
  print("Not in the list")
#Red is in the list4

print '----------------For loop---------------------'
freedom_fighters = ["Lala Lajipati Rai", "Dadabhai Naoroji", "Rajendra Prasad", "Sarojini Naidu", "Dadabhai Naoroji", "Lal Bahadur Shastri"]
print freedom_fighters
for each in freedom_fighters:
print each

#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Rajendra Prasad', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']
#Lala Lajipati Rai
#Dadabhai Naoroji
#Rajendra Prasad
#Sarojini Naidu
#Dadabhai Naoroji
#Lal Bahadur Shastri

print '----------------While loop---------------'
#Try to avoild While loops, use only unless otherwise reequired
#If you sometimes don't handle it, it may end up in infinite loop
i = 0
squares = []
while(i < 10):
squares.append(i**2)
i += 1
print squares
#[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

Learning For While loops in Python

#!/usr/local/bin/python2.7

'''
    Learning For/While loops in Python
    File name: for_while_loop_python.py
    Author: Prabhath Kota
    Date: June 22, 2018
    Python Version: 2.7
'''

'''
Topics:
For loop
While loop
range
break
continue
enumerate
'''

print '----------------For loop---------------------'
freedom_fighters = ["Lala Lajipati Rai", "Dadabhai Naoroji", "Rajendra Prasad", "Sarojini Naidu", "Dadabhai Naoroji", "Lal Bahadur Shastri"]
print freedom_fighters
for each in freedom_fighters:
print each

print '----------------For loop Break---------------------'
print freedom_fighters
#Print only first 4 elements using Break statement
#Enumerate will get you index of the element as well - starting from 0
#enumerate(freedom_fighters) will start the index from 0
#enumerate(freedom_fighters, 1) will start the index from 1
for index,each in enumerate(freedom_fighters, 1):
print index, each
if index == 4:
break
print '----------------For loop Continue---------------------'
print freedom_fighters
#Print only even elements from the list
for index,each in enumerate(freedom_fighters, 1):
if index % 2 == 1: #Odd elements
continue
else: #Even Elements
print index, each

print '----------------For loop Range---------------' 
squares = []
print range(1,10)
for x in range(0,10):
squares.append(x**2)
print (squares)

print '----------------While loop---------------'
#Try to avoild While loops, use only unless otherwise reequired
#If you sometimes don't handle it, it may end up in infinite loop
i = 0
squares = []
while(i < 10):
squares.append(i**2)
i += 1
print squares

Output:

----------------For loop---------------------

['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Rajendra Prasad', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']

Lala Lajipati Rai

Dadabhai Naoroji

Rajendra Prasad

Sarojini Naidu

Dadabhai Naoroji

Lal Bahadur Shastri

----------------For loop Break---------------------

['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Rajendra Prasad', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']

1 Lala Lajipati Rai

2 Dadabhai Naoroji

3 Rajendra Prasad

4 Sarojini Naidu

----------------For loop Continue---------------------

['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Rajendra Prasad', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']

2 Dadabhai Naoroji

4 Sarojini Naidu

6 Lal Bahadur Shastri

----------------For loop Range---------------

[1, 2, 3, 4, 5, 6, 7, 8, 9]

[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

----------------While loop---------------

[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

[Finished in 0.2s]

For Loop in Perl

FOR Loop Syntax in Perl:

Syntax: 
for (initialization; test; re-initialization) BLOCK


#!/usr/bin/perl

use strict;
use warnings;

print "\nStart For Loop"; 

for ($count = 1; $count <= 5; $count++) {
  print "\nEach Element : " . $count;
}
print "\nEnd For Loop"; 

O/P:

Start For Loop
Each Element : 1
Each Element : 2
Each Element : 3
Each Element : 4
Each Element : 5
End For Loop