# Python List: Advanced - Exercises, Practice, Solution

## Python Advanced List [15 exercises with solution]

You may read our Python list tutorial before solving the following exercises.

[An editor is available at the bottom of the page to write and execute the scripts.  Go to the editor]

1. Write a Python function to reverse a list at a specific location.
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2. Write a Python function find the length of the longest increasing sub-sequence in a list.
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3. Write a Python function that finds all the permutations of the members of a list.
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4. Write a Python function to find the kth smallest element in a list.
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5. Write a Python function to find the kth largest element in a list.
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6. Write a Python function to check if a list is a palindrome or not. Return true otherwise false.
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7. Write a Python a function to find the union and intersection of two lists.
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8. Write a Python function to remove duplicates from a list while preserving the order.
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9. Write a Python a function to find the maximum sum sub-sequence in a list. Return the maximum value.
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10. Write a Python a function to find the minimum sum sub-sequence in a list. Return the sub-sequence.
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11. Write a Python function to find the longest common sub-sequence in two lists.
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12. Write a Python program to find the first non-repeated element in a list.
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13. Write a Python a function to implement a LRU cache.
From Wikipedia -
Least recently used (LRU)
Discards the least recently used items first. This algorithm requires keeping track of what was used when, which is expensive if one wants to make sure the algorithm always discards the least recently used item. General implementations of this technique require keeping "age bits" for cache-lines and track the "Least Recently Used" cache-line based on age-bits. In such an implementation, every time a cache-line is used, the age of all other cache-lines changes. LRU is actually a family of caching algorithms with members including 2Q by Theodore Johnson and Dennis Shasha, and LRU/K by Pat O'Neil, Betty O'Neil and Gerhard Weikum.
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14. Write a Python function to sort a list of dictionaries based on values of a key.
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15. Write a Python program to find all the pairs in a list whose sum is equal to a given value.
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## List: Cheat Sheet

Making a list:

```colors = ['Red', 'Blue', 'Green', 'Black', 'White']
```

Accessing elements:

```# Getting the first element
first_col = colors
# Getting the second element
second_col = colors
# Getting the last element
```

Modifying individual items:

```# Changing an element
colors = 'Yellow'
colors[-2] = 'Red'
```

```# Adding an element to the end of the list
colors.append('Orange')
# Starting with an empty list
colors = []
colors.append('Red')
colors.append('Blue')
colors.append('Green')
# Inserting elements at a particular position
colors.insert(0, 'Violet')
colors.insert(2, 'Purple')
```

Removing elements:

```# Deleting an element by its position
del colors[-1]
# Removing an item by its value
colors.remove('Green')
```

Popping elements:

```# Pop the last item from a list
most_recent_col = colors.pop()
print(most_recent_col)
# Pop the first item in a list
first_col = colors.pop(0)
print(first_col)
```

List length:

```# Find the length of a list
num_colors = len(colors)
print("We have " + str(num_colors) + " colors.")
```

Sorting a list:

```# Sorting a list permanently
colors.sort()
# Sorting a list permanently in reverse alphabetical order
colors.sort(reverse=True)
# Sorting a list temporarily
print(sorted(colors))
print(sorted(colors, reverse=True))
# Reversing the order of a list
colors.reverse()
```

Looping through a list:

```# Printing all items in a list
for col in colors:
print(col)
# Printing a message for each item, and a separate message afterwards
for col in colors:
print("Welcome, " + col + "!")
print("Welcome, we're glad to see you all!")
```

The range() function:

```# Printing the numbers 0 to 2000
for num in range(2001):
print(num)
# Printing the numbers 1 to 2000
for num in range(1, 2001):
print(num)
# Making a list of numbers from 1 to a million
nums = list(range(1, 1000001))
```

Simple statistics:

```# Finding the minimum value in a list
nums = [23, 22, 44, 17, 77, 55, 1, 65, 82, 2]
num_min = min(nums)
# Finding the maximum value
nums = [23, 22, 44, 17, 77, 55, 1, 65, 82, 2]
num_max = max(nums)
# Finding the sum of all numbers
nums = [23, 22, 44, 17, 77, 55, 1, 65, 82, 2]
total_num = sum(nums)
```

Slicing a list:

```# Getting the first three items
colors = ['Red', 'Blue', 'Green', 'Black', 'White']
first_three = colors [:3]
# Getting the middle three items
middle_three = colors[1:4]
# Getting the last three items
last_three = colors[-3:]
```

Copying a list:

```# Making a copy of a list
colors = ['Red', 'Blue', 'Green', 'Black', 'White']
copy_of_colors = colors[:]
```

List of Comprehensions:

```# Using a loop to generate a list of square numbers
squr = []
for x in range(1, 11):
sq = x**2
squr.append(sq)
# Using a comprehension to generate a list of square numbers
squr = [x**2 for x in range(1, 11)]
# Using a loop to convert a list of names to upper case
colors = ['Red', 'Blue', 'Green', 'Black', 'White']
upper_cols = []
for cols in colors:
upper_cols.append(cols.upper())
# Using a comprehension to convert a list of names to upper case
colors = ['Red', 'Blue', 'Green', 'Black', 'White']
upper_cols = [cols.upper() for cols in colors]
```

## Python Code Editor:

More to Come !

Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page.

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﻿

## Python: Tips of the Day

Get Current Process Id:

```import os
os.getpid()
```
`21423`

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