Create a function batches that returns the maximum number of whole batches that can be cooked from a recipe.
/**
It accepts two objects as arguments: the first object is the recipe
for the food, while the second object is the available ingredients.
Each ingredient's value is number representing how many units there are.
`batches(recipe, available)`
*/
// 0 batches can be made
batches(
{ milk: 100, butter: 50, flour: 5 },
{ milk: 132, butter: 48, flour: 51 }
)
batches(
{ milk: 100, flour: 4, sugar: 10, butter: 5 },
{ milk: 1288, flour: 9, sugar: 95 }
)
// 1 batch can be made
batches(
{ milk: 100, butter: 50, cheese: 10 },
{ milk: 198, butter: 52, cheese: 10 }
)
// 2 batches can be made
batches(
{ milk: 2, sugar: 40, butter: 20 },
{ milk: 5, sugar: 120, butter: 500 }
)Answer We must have all ingredients of the recipe available, and in quantities that are more than or equal to the number of units required. If just one of ingredients is not available or lower than needed, we cannot make a single batch.
Use Object.keys() to return the ingredients of the recipe as an array, then use Array.prototype.map() to map each ingredient to the ratio of available units to the amount required by the recipe. If one of the ingredients required by the recipe is not available at all, the ratio will evaluate to NaN, so the logical OR operator can be used to fallback to 0 in this case.
Use the spread ... operator to feed the array of all the ingredient ratios into Math.min() to determine the lowest ratio. Passing this entire result into Math.floor() rounds down to return the maximum number of whole batches.
const batches = (recipe, available) =>
Math.floor(
Math.min(...Object.keys(recipe).map(k => available[k] / recipe[k] || 0))
)