Hydrothermal Venture - Advent of Code 2021 Day 5

Today's problem involves trying to avoid all points where underwater hydrothermal vents overlap. 

A full description of the problem can be found here  - https://adventofcode.com/2021/day/5

Understanding the problem

The given input file contains coordinates of hydrothermal vents. The co-ordinates only include the start and end positions. Hydrothermal vents can be vertical, horizontal and diagonal (at 45 degrees). The goal is to find the numbers of points at which these vents overlap 

Solving it

• For the first hydrothermal vent create a set of co-ordinates and put it in a set
• [ "0:9" , "1:9" , "2:9" , "3:9", "4:9" , "5:9" ]
• For subsequent hydrothermal vents create a set of co-ordinates and compare to set.
• if it exists put in a overlapped set and remove from original set
• else add it to original set
• Solution is the length of the overlapped set

Code

I decided to implement this in Python as I am trying to brush up on my language skills here

with open('input.txt') as f:
    lines = f.readlines()

vents = set()       # vent coordinates
overlapped = set()  # vent coordinates that have overlapped atleast twice

def coordinate(x,y):
    # return str(x) + ":" + str(y)
    return ( x , y )

def getAllVentCoordinates(point1,point2):
    
    point1x,point1y = [ int(i) for i in point1.split(",") ]
    point2x,point2y = [ int(i) for i in point2.split(",") ]

    print(point1,point2)

    if point1x == point2x : # x co-ordinates are the same hence vertical line
        start, end = sorted([ point1y, point2y ])
        return  { coordinate(point1x,i) for i in range(start,end+1) }
    elif point1y == point2y : # y co-ordinates are the same hence horizontal line
        start, end = sorted([ point1x, point2x ])
        return  { coordinate(i,point1y) for i in range(start,end+1) } 
    else: # diagonal lines
        xDir = 1 if point1x < point2x else -1
        yDir = 1 if point1y < point2y else -1
        ret =  { coordinate(point1x + (i*xDir), point1y + (i*yDir))  for i in range(0, abs(point1x - point2x) + 1) }
        return ret


# Using for loop
for i in lines:
    
    point1,point2 = i.replace('\n','').split(" -> ")
    ventCoordinates = getAllVentCoordinates(point1,point2)

    # print(ventCoordinates)

    if len(ventCoordinates) != 0:

        if len(vents) == 0:
            vents = ventCoordinates # initialize if first time generating co-ordinates
        else:
            for i in ventCoordinates:
                if i in vents:         # if it already exists
                    vents.remove(i)    # move it to the overlapped set
                    overlapped.add(i)
                elif i not in overlapped:
                    vents.add(i)       # otherwise add it to the set of vents

print(len(overlapped))