diff --git a/Sprint-2/improve_with_caches/fibonacci/fibonacci.py b/Sprint-2/improve_with_caches/fibonacci/fibonacci.py index 60cc667..36495d1 100644 --- a/Sprint-2/improve_with_caches/fibonacci/fibonacci.py +++ b/Sprint-2/improve_with_caches/fibonacci/fibonacci.py @@ -1,4 +1,17 @@ +# Create a dictionary to use as our "Notepad" (Cache) +memo = {} + def fibonacci(n): + # Check if we already calculated this number + if n in memo: + return memo[n] + if n <= 1: return n - return fibonacci(n - 1) + fibonacci(n - 2) + + result = fibonacci(n - 1) + fibonacci(n - 2) + + # Save the result in our Notepad before returning + memo[n] = result + + return result \ No newline at end of file diff --git a/Sprint-2/improve_with_caches/making_change/making_change.py b/Sprint-2/improve_with_caches/making_change/making_change.py index 255612e..ca82e0b 100644 --- a/Sprint-2/improve_with_caches/making_change/making_change.py +++ b/Sprint-2/improve_with_caches/making_change/making_change.py @@ -1,5 +1,6 @@ from typing import List +cache = {} def ways_to_make_change(total: int) -> int: """ @@ -7,6 +8,8 @@ def ways_to_make_change(total: int) -> int: For instance, there are two ways to make a value of 3: with 3x 1 coins, or with 1x 1 coin and 1x 2 coin. """ + # Clear cache before starting new calculation + cache.clear() return ways_to_make_change_helper(total, [200, 100, 50, 20, 10, 5, 2, 1]) @@ -14,9 +17,22 @@ def ways_to_make_change_helper(total: int, coins: List[int]) -> int: """ Helper function for ways_to_make_change to avoid exposing the coins parameter to callers. """ + # We use tuple(coins) because lists cannot be keys. + key = (total, tuple(coins)) + + if key in cache: + return cache[key] + if total == 0 or len(coins) == 0: return 0 + # Check if only one coin type remains + if len(coins) == 1: + if total % coins[0] == 0: + return 1 + else: + return 0 + ways = 0 for coin_index in range(len(coins)): coin = coins[coin_index] @@ -29,4 +45,7 @@ def ways_to_make_change_helper(total: int, coins: List[int]) -> int: intermediate = ways_to_make_change_helper(total - total_from_coins, coins=coins[coin_index+1:]) ways += intermediate count_of_coin += 1 + + # Store result in cache + cache[key] = ways return ways