I got told about this fantastic coding challenge site Advent of Code, which publishes a new pair of coding challenges every day from December 1st until Christmas Day.

Unfortunately I didn’t get the chance to start until January, but the challenges are still there at time of writing, so hopefully I will be able to make my way through them as I get time through 2021.

I will add my solutions below so you can compare; as always, it’s unlikely to be the most elegant answer but it works! I’ve only reproduced answers to part 2 of each challenge, which has always been a harder variant of part 1 so far.

#### Day 1 – Report Repair

```#open text file
with open("C:\\aoc1.txt") as file:
#create a list from lines in the file
#strip whitespace and convert string to integer for maths
data = [int(x.strip()) for x in data]
#loop through every combo until match condition found
for i in data:
for j in data:
for k in data:
if i + j + k == 2020:
print(i * j * k)
```

#### Day 2 – Password Philosophy

```#read in data from the file and create a list of lines
with open("C:\\aoc2.txt") as file:
#create lists of three members, each containing specific parameter
data = [x.split() for x in data]
#initiate counter
count = 0
#loop through each parameter list
#from first parameter, split the numbers, convert to integers and assign vars
low, high = int(params[0]), int(params[1])
#set variable to search parameter
#set variable to parameter to search
#set the match condition and perform the count
if ((source[low-1] == target) or (source[high-1] == target)) and (source[low-1] != source[high-1]):
count += 1
print(count)
```

#### Day 3 – Toboggan Trajectory

```#open file and create a list of lines
with open("C:\\aoc3.txt") as file:
data = [line.strip() for line in data]
#create function taking in slope, a list of two integers
def tree_counter(slope):
#initialise function variables
x,y,tree_count,column_count = 0,0,0,0
#create a game field from input that will accomodate the slope
while column_count < (slope[0] * len(data)):
column_count += len(data[0])
input_count = int(column_count / len(data[0]))
i = 1
new_data = data.copy()
while i < input_count:
for j in range(len(data)):
new_data[j] += data[j]
i += 1
#move through the game field counting trees
while y < len(new_data) - 1:
x, y = x + slope[0], y + slope[1]
if new_data[y][x] == '#':
tree_count += 1
return tree_count
#run the function for provided inputs
a1 = tree_counter([1,1])
a2 = tree_counter([3,1])
a3 = tree_counter([5,1])
a4 = tree_counter([7,1])
a5 = tree_counter([1,2])
#calculate condition
answer = a1 * a2 * a3 * a4 * a5