Question

We want make a package of goal kilos of chocolate. We have small bars (1 kilo each) and big bars (5 kilos each). Return the number of small bars to use, assuming we always use big bars before small bars. Return -1 if it can't be done.

makeChocolate(4, 1, 9) → 4
makeChocolate(4, 1, 10) → -1
makeChocolate(4, 1, 7) → 2

Answer 1

To solve this problem, we can use a combination of basic algebra and logic. We want to find the number of small bars to use, assuming we always use big bars before small bars. If the number of small bars required is less than or equal to the available small bars, we return the number of small bars required. Otherwise, we return -1.

Step-by-step explanation:

To solve this problem, we can use a combination of basic algebra and logic. We want to find the number of small bars to use, assuming we always use big bars before small bars. If we have n big bars and m small bars, we can determine the number of small bars required using the equation 5n + m = goal. If the equation is solvable, we check if the number of small bars required is less than or equal to the available small bars. If it is, we return the number of small bars required. Otherwise, we return -1.

Let's take an example: makeChocolate(4, 1, 9). Here, we have 4 big bars, 1 small bar, and the goal is 9 kilos. Using the equation 5n + m = goal, we obtain the equation 5*4 + m = 9. Solving for m gives us m = 9 - 5*4, which simplifies to m = 9 - 20 and finally m = -11. Since the number of small bars cannot be negative, we return -1 in this case.

In the case of makeChocolate(4, 1, 7), we can solve the equation 5*4 + m = 7 to find m = 7 - 20 = -13. Again, since the number of small bars cannot be negative, we return -1.

Finally, let's consider makeChocolate(4, 1, 10). Solving the equation 5*4 + m = 10 gives us m = 10 - 20 = -10. Again, we return -1 because the number of small bars cannot be negative.