Skip to content

Instantly share code, notes, and snippets.

Created Dec 8, 2020
What would you like to do?
from sys import exit
inputData = list()
with open('input.txt', 'r') as infile:
for line in infile:
inst, val = line.split(' ')[0], int(line.split(' ')[1])
inputData.append([inst, val])
#Returns a tuple of (Did the loop terminate?, accumulator value at exit)
def accumulatorValueBeforeLoop(data):
workingData = [[d[0], d[1]] for d in data]
accumulator = 0
head = 0
seenInstructions = set()
while head not in seenInstructions:
#Added to detect the instruction-past-end-of-data requirement for Part 2
if head == len(workingData):
return accumulator, True
#print(f"Processing instruction @ {head}: {workingData[head][0]},{workingData[head][1]}")
if workingData[head][0] == 'nop':
head += 1
elif workingData[head][0] == 'acc':
accumulator += data[head][1]
head += 1
elif workingData[head][0] == 'jmp':
head += data[head][1]
return accumulator, False
#Swaps the given position (pos) nop to jmp or jmp to nop as applicable;
#Returns (accumulator value, True if program terminated by running off the end, false if it loops)
def solveWithSwaps(baseData, pos):
if baseData[pos][0] in ('jmp', 'nop'):
testData = [[d[0], d[1]] for d in baseData] #Breaks the input list appart to pass by value instead of by reference
if testData[pos][0] == 'jmp':
testData[pos][0] = 'nop'
elif testData[pos][0] == 'nop':
testData[pos][0] = 'jmp'
raise ValueError(f"Unknown instruction {testData[pos][0]}")
#print(f"Running test with position {pos} changed to {testData[pos][0]} ", end = "")
result = accumulatorValueBeforeLoop(testData)
return result
return (0, False)
if __name__ == '__main__':
print(f"Solution to part 1 is: {accumulatorValueBeforeLoop(inputData)[0]}")
for i in range(len(inputData)):
result = solveWithSwaps(inputData, i)
if result[1] == True: print(f"Solution to part 2 is: {result[0]}")
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment