# 100 Days of Code Day 16 - Problem Solving  Hello! My name is Rick and I am in search for gig as a developer :)

This past December I finished up a year long study with a full-stack school in NYC called Codeimmersives. We explored HTML, CSS, JavaScript, and how to build applications using the MERN stack. I learned about class-based components, passing props around (prop-drilling) and utilizing the component lifecycle(componentWillMount, componentDidMount, etc). After learning class based components, we moved on to functional based components using hooks, custom hooks, and different ways to manage state, such as the useContext and Redux APIs. (This is just a brief overview of the technologies I studied over the past year). Currently I am enrolled at devCodeCamp learning the basics of Python. I am documenting my journey by sharing these blog posts. Please help me out by dropping a comment below on what you think!

I spent most of today solving the problems below in the block of code. (Python) It really helps to break down the problem into smaller chucks before typing in the IDE.

``````# 1. Reverse a string

# a. Write code that takes a string as input and returns the string reversed

# b. i.e. “Hello” will be returned as “olleH”

def reverse_str(string):
return string[::-1]

print(reverse_str('Hello'))

# 2. Capitalize letter

# a. Write code that takes a string as input and capitalize the first letter of each word. Words will be separated by only one space. i.e. “hello world” should be outputted as “Hello World”

def cap_first_letter(string):
return string.capitalize()

print(cap_first_letter('hello world'))

# 3. Compress a string of characters

# a. For example, an input of "aaabbbbbccccaacccbbbaaabbbaaa" would compress to "3a5b4c2a3c3b3a3b3a" "3a5b4c2a3c3b3a3b3a"

def compress_str(string):
count = 0
char_in_question =''
new_string = ''
for char in string:
if char_in_question != '' and char_in_question != char:
new_string += str(count) + char_in_question
count = 0
if char == char_in_question:
count += 1
else:
char_in_question = char
count = 1
new_string += str(count) + char_in_question
return new_string

print(compress_str('aaabbbbbccccaacccbbbaaabbbaaa'))

# 4. BONUS CHALLENGE: Palindrome

# a. A word, phrase, or sequence that reads the same backward as forward i.e. madam

# b. Write code that takes a user input and checks to see if it is a Palindrome and reports the result

def is_palindrome(string):
reversed_string = string[::-1]
if reversed_string == string:
return 'This is a Palindrome!'
else:
return 'This is not a Palindrome!'

print(is_palindrome('bubble'))

# 1. Happy Numbers a. https://en.wikipedia.org/wiki/Happy_number

# b. A happy number is a number defined by the following process: starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1. An example of a happy number is 19

# c. Write a method that determines if a number is happy or sad

def is_happy_num(num):
nums = str(num)
newNum = 0
for num in nums:
num = int(num)**2
newNum += num
if newNum == 1:
return 'This is a happy number!'
elif newNum < 10 and newNum != 1:
return 'This is not a happy number!'
return is_happy_num(newNum)

print(is_happy_num(19))

print(is_happy_num(4))

# 2. Prime Numbers

# a. A prime number is a number that is only divisible by one and itself.

# b. Write a method that prints out all prime numbers between 1 and 100

def prime_checker(num):
is_prime = True
if(num == 2):
return is_prime
else:
for i in range(2, num):
if(num % i == 0):
is_prime = False
return is_prime

def show_prime_nums_to_100():

for number in range(2,100):
if prime_checker(number):
print(number)

print(show_prime_nums_to_100())

# 3. Fibonacci

# a. A series of numbers in which each number (Fibonacci number) is the sum of the two preceding numbers. The simplest is the series 1, 1, 2, 3, 5, 8, etc.

# b. Write a method that does the Fibonacci sequence starting at 1

def is_fibonacci():
my_list = [1,1]

for i in range(2,14):
new_val = my_list[i - 1] + my_list[i - 2]
my_list.append(new_val)
return my_list

print(is_fibonacci())

# c. HARDER VERSION: Write a method that does the Fibonacci sequence starting at a number that a user inputs

def is_fibonacci(starting_num):
my_list = [starting_num,starting_num]

for i in range(2,14):
new_val = my_list[i - 1] + my_list[i - 2]
my_list.append(new_val)
return my_list

print(is_fibonacci(3))

# Steps of the software development process:
# 1. Based on a given starting point (feature, task, code block, etc.), what is the
# expected end result?
# 2. What are the written-out steps to go from point A to point B? You need to
# solve the problem before you begin coding it.
# 3. Implementation (coding it out, researching)
# 4. Test and debug code (run code with breakpoint, unit test, etc.)
# 5. Refactor if necessary. Test again. This continues until functionality is
# solidified.
# The above steps should be rinse and repeated for every single problem you
# encounter. Ignoring these steps or straying from them will result in the long way
# around to solving a problem or even possibly never solving the problem.
# To be a good problem solver, it is important to be able to break problems down.
# One way to go about this is to write out the steps it will take to solve the problem.
# These steps are written down in English in a manner that are easily explainable to
# someone who may not be technical. The idea is that in order to code something out,
# you first need to have a good understanding of what it is you are attempting to
# solve. For each of the problems below, write out the steps it will take to go about
# solving the problem. Then code it out and test!
# You may jump around in these problems. If you get stuck on one problem, begin
# working on another. If you get stuck on that new problem, go back to working on
# the previous one.
# The use cases below are just examples to give you a better idea of what might be
# passed into the method or what might be outputted from the method. You shouldn’t
# be coding exactly to these examples, but rather, be flexible to handle any data of
# that data type.
# Whiteboard Challenges
# 1. Given an array of integers, return indices of the two numbers such that they
# add up to a specific target. You may assume that each input would
# have exactly one solution, and you may not use the same element twice.
# a. Use Case:
# i. Given numbers in an array: [5, 17, 77, 50]
# ii. Target: 55

def find_indices(list, target):
# check each index of possible pairs to see if they add to target number
for i in range(0,len(list)):
for j in range(i,len(list)):
if list[i] + list[j] == target:
# expected end result is two numbers
return [i,j]

print(find_indices([2,3,4,22,4,6], 28))

# 2. Given a number, return the reciprocal of the reverse of the original number,
# as a double.
# a. Use case: If given 17, return 0.01408 (1/71)

def recip_reverse(num):
# make string
num = str(num)
# reverse string
num = num[::-1]
# reciprocal
num = 1/int(num)
# format 5 decimal places to right
num = "{:.5f}".format(num)
return num

print(recip_reverse(17))

# 3. A briefcase has a four-digit rolling-lock. Each digit is a number from 0-9 that
# can be rolled either forwards or backwards. Write a method that returns the
# smallest number of turns it takes to transform the lock from current
# combination to the target combination. One turn is equivalent to rolling a
# number forwards or backwards by one.
# a. Use case:
# i. Current lock: 3893
# ii. Target lock: 5296

def to_str(char):
return str(char)

def how_many_turns(current_lock, target_lock):
# parse to str for iteration
current_lock = str(current_lock)
target_lock = str(target_lock)
# est count var to keep count of distance
count = 0
for i in range(0,len(current_lock)):
# make sure to continue if same
if current_lock[i] == target_lock[i]:
continue
num1 = int(current_lock[i])
num2 = int(target_lock[i])
# little math to compensate for index 0-9
if num1 < num2:
count += num2 - num1
else:
count += (num2 + 10) - num1
# return count
return count
print(how_many_turns(3893, 5296))

# 4. Given a list of integers, return a bool that represents whether or not all
# integers in the list can form a sequence of incrementing integers
# a. Use case:
# i. {5, 7, 3, 8, 6}  false (no 4 to complete the sequence)
# ii. {17, 15, 20, 19, 21, 16, 18}  true

def can_sort_by_increments(list_of_nums):
list_of_nums.sort()
for i in range(1,len(list_of_nums)):
num1 = list_of_nums[i - 1]
num2 = list_of_nums[i]
if num2 != num1 + 1:
return False
return True

print(can_sort_by_increments([5, 7, 3, 8, 6]))

# 5. Create a method that takes an array of positive and negative numbers.
# Return an array where the first element is the count of the positive numbers
# and the second element is the sum of negative numbers.
# a. Use case: [7, 9, -3, -32, 107, -1, 36, 95, -14, -99, 21]

# 6. Create a method that accepts a string of space separated numbers and
# returns the highest and lowest number as a string
# a. Use case: “3 9 0 1 4 8 10 2”  “0 10”
# 7. Create a method that accepts a string, check if it’s a valid email address and
# returns either true or false depending on the valuation. Think about what is
# necessary to have a valid email address.
# a. Use case:
# i. “mike1@gmail.com”  true
# ii. “gmail.com”  false
# 8. Create a method that takes in a string and replaces each letter with its
# appropriate position in the alphabet and returns the string
# a. Use case:
# i. “abc”  “1 2 3”
# ii. “coding is fun”  “3 15 4 9 14 7 9 19 6 21 14”
``````