Julia

I did not try to make my solution concise and kept separate code for part 1 and part 2 with test cases for both to check if I broke anything. But after struggling with Day 2 I am quite pleased to have solved Day 3 with only a little bugfixing.

function calcLineResult(line::String)
	lineResult::Int = 0
	enabled::Bool = true
	for i=1 : length(line)
		line[i]!='m' ? continue : (i<length(line) ? i+=1 : continue)
		line[i]!='u' ? continue : (i<length(line) ? i+=1 : continue)
		line[i]!='l' ? continue : (i<length(line) ? i+=1 : continue)
		line[i]!='(' ? continue : (i<length(line) ? i+=1 : continue)
		num1Str::String = ""
		while line[i] in ['0','1','2','3','4','5','6','7','8','9'] #should check for length of digits < 3, but works without
			num1Str = num1Str*line[i]; (i<length(line) ? i+=1 : continue)
		end
		line[i]!=',' ? continue : (i<length(line) ? i+=1 : continue)
		num2Str::String = ""
		while line[i] in ['0','1','2','3','4','5','6','7','8','9'] #should check for length of digits < 3, but works without
			num2Str = num2Str*line[i]; (i<length(line) ? i+=1 : continue)
		end
		line[i]==')' ? lineResult+=parse(Int,num1Str)*parse(Int,num2Str) : continue
	end
	return lineResult
end

function calcLineResultWithEnabling(line::String,enabled::Bool)
	lineResult::Int = 0
	for i=1 : length(line)
		if enabled && line[i] == 'm'
			i<length(line) ? i += 1 : continue
			line[i]!='u' ? continue : (i<length(line) ? i+=1 : continue)
			line[i]!='l' ? continue : (i<length(line) ? i+=1 : continue)
			line[i]!='(' ? continue : (i<length(line) ? i+=1 : continue)
			num1Str::String = ""
			while line[i] in ['0','1','2','3','4','5','6','7','8','9']
				num1Str = num1Str*line[i]; (i<length(line) ? i+=1 : continue)
			end
			line[i]!=',' ? continue : (i<length(line) ? i+=1 : continue)
			num2Str::String = ""
			while line[i] in ['0','1','2','3','4','5','6','7','8','9']
				num2Str = num2Str*line[i]; (i<length(line) ? i+=1 : continue)
			end
			line[i]==')' ? lineResult+=parse(Int,num1Str)*parse(Int,num2Str) : continue
		elseif line[i] == 'd'
			i<length(line) ? i += 1 : continue
			line[i]!='o' ? continue : (i<length(line) ? i+=1 : continue)
			if line[i] == '('
				i<length(line) ? i += 1 : continue
				line[i]==')' ? enabled=true : continue
				#@info i,line[i-3:i]
			elseif line[i] == 'n'
				i<length(line) ? i += 1 : continue
				line[i]!=''' ? continue : (i<length(line) ? i+=1 : continue)
				line[i]!='t' ? continue : (i<length(line) ? i+=1 : continue)
				line[i]!='(' ? continue : (i<length(line) ? i+=1 : continue)
				line[i]==')' ? enabled=false : continue
				#@info i,line[i-6:i]
			else
				nothing
			end
		end
	end
	return lineResult,enabled
end

function calcMemoryResult(inputFile::String,useEnabling::Bool)
	memoryRes::Int = 0
	f = open(inputFile,"r")
	lines = readlines(f)
	close(f)
	enabled::Bool = true
	for line in lines
		if useEnabling
			lineRes::Int,enabled = calcLineResultWithEnabling(line,enabled)
			memoryRes += lineRes
		else
			memoryRes += calcLineResult(line)
		end
	end
	return memoryRes
end

if abspath(PROGRAM_FILE) == @__FILE__
	@info "Part 1"
	@debug "checking test input"
	inputFile::String = "day03InputTest"
	memoryRes::Int = calcMemoryResult(inputFile,false)
	try
		@assert memoryRes==161
	catch e
		throw(ErrorException("$e memoryRes=$memoryRes"))
	end
	@debug "test input ok"
	@debug "running real input"
	inputFile::String = "day03Input"
	memoryRes::Int = calcMemoryResult(inputFile,false)
	try
		@assert memoryRes==153469856
	catch e
		throw(ErrorException("$e memoryRes=$memoryRes"))
	end
	println("memory result: $memoryRes")
	@debug "real input ok"

	@info "Part 2"
	@debug "checking test input"
	inputFile::String = "day03InputTest"
	memoryRes::Int = calcMemoryResult(inputFile,true)
	try
		@assert memoryRes==48
	catch e
		throw(ErrorException("$e memoryRes=$memoryRes"))
	end
	@debug "test input ok"
	@debug "running real input"
	inputFile::String = "day03Input"
	memoryRes::Int = calcMemoryResult(inputFile,true)
	try
		@assert memoryRes==77055967
	catch e
		throw(ErrorException("$e memoryRes=$memoryRes"))
	end
	println("memory result: $memoryRes")
	@debug "real input ok"

end