chore: add different approach for 2021 day 7

Author: marcelblijleven

src/adventofcode/year_2021/day_07_2021.py

@@ -1,8 +1,10 @@
+from statistics import median
 from typing import List
 
 from adventofcode.util.exceptions import SolutionNotFoundException
 from adventofcode.util.helpers import solution_timer
 from adventofcode.util.input_helpers import get_input_for_day
+from adventofcode.util.math_helpers import mean_floor, mean_ceil, gaussian_sum
 
 
 def get_crabs(input_data: List[str]) -> List[int]:
@@ -18,6 +20,34 @@ def move_to_position(crabs: List[int], position: int) -> int:
     return fuel
 
 
+def get_least_amount_of_fuel(crabs: List[int]) -> int:
+    return move_to_position(crabs, int(median(crabs)))
+
+
+def get_least_amount_of_fuel_part_two(crabs: List[int]) -> int:
+    crabs.sort()
+    mean_crabs_floor = mean_floor(crabs)
+    mean_crabs_ceil = mean_ceil(crabs)
+
+    return min(
+        sum(gaussian_sum(abs(crab - mean_crabs_floor)) for crab in crabs),
+        sum(gaussian_sum(abs(crab - mean_crabs_ceil)) for crab in crabs),
+    )
+
+
+def get_least_amount_of_fuel_part_two_slower(crabs: List[int]) -> int:
+    crabs.sort()
+    mid = crabs[len(crabs) // 2]
+
+    fuel = sum(gaussian_sum(abs(crab - mid)) for crab in crabs)
+
+    for position in range(min(crabs[mid:]), max(crabs) + 1):
+        position_fuel = min(fuel, sum(gaussian_sum(abs(crab - position)) for crab in crabs))
+        fuel = min(fuel, position_fuel)
+
+    return fuel
+
+
 def try_all_positions(crabs: List[int]) -> int:
     fuel = int(1e10)
     crabs.sort()
@@ -36,7 +66,7 @@ def try_all_positions(crabs: List[int]) -> int:
 @solution_timer(2021, 7, 1)
 def part_one(input_data: List[str]):
     crabs = get_crabs(input_data)
-    answer = try_all_positions(crabs)
+    answer = get_least_amount_of_fuel(crabs)
 
     if not answer:
         raise SolutionNotFoundException(2021, 7, 1)
@@ -46,7 +76,8 @@ def part_one(input_data: List[str]):
 
 @solution_timer(2021, 7, 2)
 def part_two(input_data: List[str]):
-    answer = ...
+    crabs = get_crabs(input_data)
+    answer = get_least_amount_of_fuel_part_two(crabs)
 
     if not answer:
         raise SolutionNotFoundException(2021, 7, 2)