aoc22/day9-2.py

gridVisited =[['#']]
posHead = [0, 0]
posTail = []

# drawgrid only used for visualized debugging
def drawGrid():
    visualGrid = []

    for yCoord in range(len(gridVisited)):
        visualGridLine = []

        for xCoord in range(len(gridVisited[0])):
            if posHead[0] == yCoord and posHead[1] == xCoord:
                visualGridLine.append('H')
                continue

            haveAppended = False
            for tp in range(9):
                if posTail[tp][0] == yCoord and posTail[tp][1] == xCoord:
                    visualGridLine.append(str(tp+1))
                    haveAppended = True
                    break

            if not haveAppended:
                if gridVisited[yCoord][xCoord] == '#':
                    visualGridLine.append('#')
                else:
                    visualGridLine.append('.')

        visualGrid.append(visualGridLine)

    for ln in visualGrid:
        print("".join(ln))

    input("Ready for next move?")

def expandGrid(direct):
    if direct == "U":
        gridVisited.insert(0, [])
        for _ in range(len(gridVisited[1])):
            gridVisited[0].append('.')
        posHead[0] = posHead[0] + 1
        for i in range(len(posTail)):
            posTail[i][0] = posTail[i][0] + 1
    elif direct == "R":
        for i in range(len(gridVisited)):
            gridVisited[i].append('.')
    elif direct == "D":
        gridVisited.append([])
        tempx = len(gridVisited) - 1
        for _ in range(len(gridVisited[0])):
            gridVisited[tempx].append('.')
    elif direct == "L":
        for i in range(len(gridVisited)):
            gridVisited[i].insert(0, '.')
        posHead[1] = posHead[1] + 1
        for i in range(len(posTail)):
            posTail[i][1] = posTail[i][1] + 1

def checkDist():
    for z in range(9):
        if z == 0:
            one = posHead
        else:
            one = posTail[z-1]
        two = posTail[z]
        tempa = one[1] - two[1]
        tempb = one[0] - two[0]
        tempc = tempa + tempb
        tempd = tempa * tempb
        if one[0] == two[0]:
            if not(tempa == 1 or tempa == -1):
                if tempa > 0:
                    posTail[z][1] += 1
                elif tempa < 0:
                    posTail[z][1] -= 1
        elif one[1] == two[1]:
            if not(tempb == 1 or tempb == -1):
                if tempb > 0:
                    posTail[z][0] += 1
                elif tempb < 0:
                    posTail[z][0] -= 1
        elif (tempc in [-1, 0, 1])  and tempb < 0 and tempd != -1:
            posTail[z][0] -= 1
            posTail[z][1] += 1
        elif tempc in [3, 4]:
            posTail[z][0] += 1
            posTail[z][1] += 1
        elif (tempc in [-1, 0, 1])  and tempb > 0 and tempd != -1:
            posTail[z][0] += 1
            posTail[z][1] -= 1
        elif tempc in [-4, -3]:
            posTail[z][0] -= 1
            posTail[z][1] -= 1

    # print(posTail[8])
    gridVisited[posTail[8][0]][posTail[8][1]] = '#'

    # drawGrid()

for _ in range(9):
    posTail.append([0,0])

with open('input9.txt','r') as f:
    inp = f.read().splitlines(keepends=False)

direction = []
distance = []

for i in inp:
    tempa, tempb = i.split(' ')
    direction.append(tempa)
    distance.append(int(tempb))

for x in range(len(direction)):
    if direction[x] == 'U':
        for y in range(distance[x]):
            if posHead[0] == 0:
                expandGrid("U")
            posHead[0] -= 1
            checkDist()
    elif direction[x] == 'R':
        for y in range(distance[x]):
            if posHead[1] == len(gridVisited[0])-1:
                expandGrid("R")
            posHead[1] += 1
            checkDist()
    elif direction[x] == 'D':
        for y in range(distance[x]):
            if posHead[0] == len(gridVisited) - 1:
                expandGrid("D")
            posHead[0] += 1
            checkDist()
    elif direction[x] == 'L':
        for y in range(distance[x]):
            if posHead[1] == 0:
                expandGrid("L")
            posHead[1] -= 1
            checkDist()

visited = 0

for i in gridVisited:
    for x in i:
        if x == '#':
            visited += 1

print(visited)