private c_snailfish_number parse_pair_element(
string input,
int start_index,
out int end_index)
{
c_snailfish_number result;
if (input[start_index] == '[')
{
int left_bracket_depth = 1;
for (end_index = start_index; left_bracket_depth > 0; end_index++)
{
switch (input[end_index + 1])
{
case '[': left_bracket_depth++; break;
case ']': left_bracket_depth--; break;
}
}
result = new c_snailfish_number(this, input.Substring(start_index, end_index - start_index + 1));
}
else
{
end_index = start_index;
while (input[end_index + 1] != ',' && input[end_index + 1] != ']')
{
end_index++;
}
result = new c_snailfish_number(this, input.Substring(start_index, end_index - start_index + 1));
}
return(result);
}
private c_snailfish_number(
c_snailfish_number p,
string input)
{
parent = p;
if (input[0] == '[')
{
type = e_snailfish_number_type.pair;
int left_start_index = 1;
int left_end_index;
left = parse_pair_element(input, left_start_index, out left_end_index);
int right_start_index = left_end_index + 2;
int right_end_index;
right = parse_pair_element(input, right_start_index, out right_end_index);
}
else
{
type = e_snailfish_number_type.raw_number;
value = UInt64.Parse(input);
}
}
private c_snailfish_number(
UInt64 v,
c_snailfish_number p)
{
type = e_snailfish_number_type.raw_number;
parent = p;
value = v;
}
public c_snailfish_number plus(
bool pretty,
c_snailfish_number other)
{
if (pretty)
{
Console.WriteLine();
Console.WriteLine("adding these:");
display(pretty);
Console.WriteLine();
other.display(pretty);
Console.WriteLine();
}
validate(this);
validate(other);
c_snailfish_number result = new c_snailfish_number(this, other, null);
validate(result);
if (pretty)
{
Console.WriteLine("equals:");
result.display(pretty);
Console.WriteLine();
}
bool reduced;
do
{
reduced = result.try_explode(pretty);
if (!reduced)
{
reduced = result.try_split(pretty);
}
if (pretty && reduced)
{
Console.WriteLine("reduced to:");
result.display(pretty);
Console.WriteLine();
}
validate(result);
} while (reduced);
return(result);
}
static void validate(c_snailfish_number number, c_snailfish_number parent = null)
{
Debug.Assert(number.parent == parent);
if (number.left != null)
{
validate(number.left, number);
}
if (number.right != null)
{
validate(number.right, number);
}
}
private c_snailfish_number(
c_snailfish_number l,
c_snailfish_number r,
c_snailfish_number p)
{
type = e_snailfish_number_type.pair;
parent = p;
left = l.clone();
left.parent = this;
right = r.clone();
right.parent = this;
}
private bool try_explode(
bool pretty,
int num_parents)
{
bool result = false;
if (type == e_snailfish_number_type.pair)
{
result = left.try_explode(pretty, num_parents + 1);
if (!result &&
num_parents >= 4)
{
if (pretty)
{
Console.WriteLine("exploding:");
display(pretty);
Console.WriteLine();
}
explode_left_value(pretty);
explode_right_value(pretty);
type = e_snailfish_number_type.raw_number;
left = null;
right = null;
value = 0;
if (pretty)
{
Console.WriteLine("into:");
display(pretty);
Console.WriteLine();
}
result = true;
}
if (!result)
{
result = right.try_explode(pretty, num_parents + 1);
}
}
return(result);
}
private void explode_right_value(
bool pretty)
{
Debug.Assert(type == e_snailfish_number_type.pair);
Debug.Assert(right.type == e_snailfish_number_type.raw_number);
UInt64 exploding_value = right.value;
c_snailfish_number current = this;
bool searching_up = true;
while (searching_up)
{
searching_up = (current.parent != null && current.parent.right == current);
current = current.parent;
}
if (current != null)
{
current = current.right;
while (current.type == e_snailfish_number_type.pair)
{
current = current.left;
}
UInt64 exploding_result = exploding_value + current.value;
if (pretty)
{
Console.WriteLine(" {0} + {1} = {2}", exploding_value, current.value, exploding_result);
}
current.value = exploding_result;
}
else
{
if (pretty)
{
Console.WriteLine(" Discarding {0}", exploding_value);
}
}
}
public bool try_split(
bool pretty)
{
bool result = false;
if (type == e_snailfish_number_type.pair)
{
result = left.try_split(pretty);
if (!result)
{
result = right.try_split(pretty);
}
}
else if (type == e_snailfish_number_type.raw_number &&
value >= 10)
{
if (pretty)
{
Console.WriteLine("splitting:");
display(pretty);
Console.WriteLine();
}
type = e_snailfish_number_type.pair;
left = new c_snailfish_number(value / 2, this);
right = new c_snailfish_number(value / 2 + value % 2, this);
value = 0;
if (pretty)
{
Console.WriteLine("into:");
display(pretty);
Console.WriteLine();
}
result = true;
}
return(result);
}
public static void Part_1(
string input,
bool pretty)
{
c_snailfish_number[] numbers = parse_input(input, pretty);
c_snailfish_number sum = numbers[0];
for (int i = 1; i < numbers.Length; i++)
{
sum = sum.plus(pretty, numbers[i]);
}
Console.WriteLine();
Console.WriteLine("final sum:");
sum.display(true);
Console.WriteLine();
Console.ForegroundColor = ConsoleColor.Green;
Console.WriteLine();
Console.WriteLine("Magnitude = {0}", sum.magnitude());
Console.ResetColor();
}
public static void Part_2(
string input,
bool pretty)
{
c_snailfish_number[] numbers = parse_input(input, pretty);
UInt64 max_magnitude = UInt64.MinValue;
for (int i = 0; i < numbers.Length; i++)
{
for (int j = 0; j < numbers.Length; j++)
{
if (i != j)
{
c_snailfish_number sum = numbers[i].plus(pretty, numbers[j]);
UInt64 magnitude = sum.magnitude();
if (pretty)
{
Console.ForegroundColor = ConsoleColor.Blue;
Console.WriteLine();
Console.WriteLine("Magnitude = {0}", magnitude);
Console.ResetColor();
}
max_magnitude = Math.Max(max_magnitude, magnitude);
}
}
}
Console.ForegroundColor = ConsoleColor.Green;
Console.WriteLine();
Console.WriteLine("Max Magnitude = {0}", max_magnitude);
Console.ResetColor();
}
