import sys

def var_index(var):
    if var == "w":
        return 0
    if var == "x":
        return 1
    if var == "y":
        return 2
    if var == "z":
        return 3
    return -1

def var_value(variables, var):
    if var == "w" or var == "x" or var == "y" or var == "z":
        return variables[var_index(var)]
    return var

def expression(index, value):
    variable = [0] * 15
    variable[index] = value
    return variable

def min_value(variable):
    result = variable[0]
    for index in range(1, 15):
        if variable[index] > 0:
            result += variable[index]
        else:
            result += variable[index] * 9
    return result

def max_value(variable):
    result = variable[0]
    for index in range(1, 15):
        if variable[index] > 0:
            result += variable[index] * 9
        else:
            result += variable[index]
    return result

instructions = []
input_data = open(r"c:\users\emurp\desktop\personal\aoc2021\24_input.txt")
for input_line in input_data.read().splitlines():
    input_line = input_line.replace("\n", "")
    if input_line.startswith("inp"):
        oper, var1_string = input_line.split(" ")
        var2_string = ""
    else:
        oper, var1_string, var2_string = input_line.split(" ")
    instruction = [oper, var1_string, var2_string]
    instructions.append(instruction)

# Determine how much the final output actually depends on the 14-digit number

max_decision_count = 7
for equality_decision in range(0, 2 ** max_decision_count):
    # print ("Start of a pass")
    decisions = []
    current_equality_decision = equality_decision
    decision_count = 0
    variables = []
    for index in range(0, 4):
        variable = [0] * 15 # coefficients of 1, d1, d2, ..., d14
        variables.append(variable)
    model_digit = 0
    for instruction in instructions:
        # print ("Evaluating", instruction)
        oper, var1, var2 = instruction
        if oper == "inp":
            model_digit += 1
            variables[var_index(var1)] = expression(model_digit, 1)
        else:
            if var2.isnumeric() or (var2[0] == "-" and var2[1:].isnumeric()):
                expr = expression(0, int(var2))
            else:
                expr = variables[var_index(var2)]
            if oper == "add":
                for index in range(0, 15):
                    variables[var_index(var1)][index] += expr[index]
            elif oper == "mul":
                for index in range(1, 15):
                    if expr[index] != 0:
                        print ("Multiplication by non-constant expression")
                        sys.exit()
                for index in range(0, 15):
                    variables[var_index(var1)][index] *= expr[0]
            elif oper == "div":
                for index in range(1, 15):
                    if expr[index] != 0:
                        print ("Division by non-constant expression")
                        sys.exit()
                if expr[0] == 0:
                    print ("Division by zero")
                    sys.exit()
                for index in range(1, 15):
                    if variables[var_index(var1)][index] % expr[0] > 0 and 9 * variables[var_index(var1)][index] >= expr[0]:
                        print ("Division leading to fractional coefficient")
                        sys.exit();
                for index in range(0, 15):
                    numerator = variables[var_index(var1)][index]
                    result = int(abs(numerator) / abs(expr[0]))
                    if (numerator > 0 and expr[0] < 0) or (numerator < 0 and expr[0] > 0):
                        result *= -1
                    variables[var_index(var1)][index] = result
            elif oper == "mod":
                for index in range(1, 15):
                    if expr[index] != 0:
                        print ("Mod by non-constant expression")
                        sys.exit()
                if expr[0] <= 0:
                    print ("Mod by", expr[0])
                    sys.exit()
                for index in range(1, 15):
                    if variables[var_index(var1)][index] % expr[0] > 0 and 9 * (variables[var_index(var1)][index] % expr[0]) >= expr[0]:
                        print ("Mod failing to zero out or no-op a coefficient")
                        sys.exit()
                for index in range(0, 15):
                    variables[var_index(var1)][index] %= expr[0]
            elif oper == "eql":
                min_val1 = min_value(variables[var_index(var1)])
                max_val1 = max_value(variables[var_index(var1)])
                min_val2 = min_value(expr)
                max_val2 = max_value(expr)
                if min_val1 > max_val2 or max_val1 < min_val2:
                    variables[var_index(var1)] = expression(0, 0)
                else:
                    needed_decision = False
                    for index in range(1, 15):
                        if variables[var_index(var1)][index] != expr[index]:
                            if decision_count == max_decision_count:
                                print ("Max decision count exceeded")
                                sys.exit()
                            decisions.append(variables[var_index(var1)])
                            decisions.append(expr)
                            if current_equality_decision % 2 == 1:
                                decisions.append("are equal")
                                variables[var_index(var1)] = expression(0, 1)
                            else:
                                decisions.append("are not equal")
                                variables[var_index(var1)] = expression(0, 0)
                            current_equality_decision /= 2
                            decision_count += 1
                            needed_decision = True
                            break
                    if not needed_decision:
                        if variables[var_index(var1)][0] == expr[0]:
                            variables[var_index(var1)] = expression(0, 1)
                        else:
                            variables[var_index(var1)] = expression(0, 0)
        # print ("w =", variables[0])
        # print ("x =", variables[1])
        # print ("y =", variables[2])
        # print ("z =", variables[3])
    if min_value(variables[3]) <= 0 and max_value(variables[3]) >= 0:
        print (decisions)
        print (variables[3])
        print ("**")
    else:
        print ("Final z value can never equal zero")
        print (variables[3])
        print ("--")
print ("Reached end")