London | 26-SDC-Mar | Craig D'Silva| Sprint 2 | Improve code with caches

Sprint-2/improve_with_caches/fibonacci/fibonacci.py

@@ -1,4 +1,9 @@
 def fibonacci(n):
     if n <= 1:
         return n
-    return fibonacci(n - 1) + fibonacci(n - 2)
+    nums = [0, 1]
+    i = 0
+    while i < n:
+        nums.append(nums[len(nums) - 1] + nums[len(nums) - 2])
+        i += 1
+    return nums[n]

Sprint-2/improve_with_caches/making_change/making_change.py

@@ -13,20 +13,12 @@ def ways_to_make_change(total: int) -> int:
 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.
-    """
-    if total == 0 or len(coins) == 0:
-        return 0
-
-    ways = 0
-    for coin_index in range(len(coins)):
-        coin = coins[coin_index]
-        count_of_coin = 1
-        while coin * count_of_coin <= total:
-            total_from_coins = coin * count_of_coin
-            if total_from_coins == total:
-                ways += 1
-            else:
-                intermediate = ways_to_make_change_helper(total - total_from_coins, coins=coins[coin_index+1:])
-                ways += intermediate
-            count_of_coin += 1
-    return ways
+    """  
+    ways = [0] * (total + 1)
+    ways[0] = 1
+
+    for coin in coins:
+        for amount in range(coin, total + 1):
+            ways[amount] += ways[amount - coin]
+
+    return ways[total]