Total a basket that came off a queue
Order lines arrive from a message queue and the payload is not always clean: a line can be missing entirely, and quantities have been seen at zero.
- A missing line contributes nothing and must not stop the sum.
- A line with a quantity of zero or less contributes nothing either.
- The total is in minor units.
orderTotal(lines: list<Line?>) → int
Go needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
func orderTotal(lines []*Line) int {
}Worked examples
| Call | Result |
|---|---|
orderTotal([]*Line{&Line{Sku: "A", Qty: 2, UnitPrice: 100}, &Line{Sku: "B", Qty: 3, UnitPrice: 50}}) | 350 |
orderTotal([]*Line{&Line{Sku: "A", Qty: 1, UnitPrice: 10}, nil, &Line{Sku: "C", Qty: 2, UnitPrice: 5}}) | 20 |
orderTotal([]*Line{&Line{Sku: "A", Qty: 0, UnitPrice: 999}, &Line{Sku: "B", Qty: -1, UnitPrice: 999}}) | 0 |
orderTotal([]*Line{}) | 0 |
Hint
Guard inside the loop, not before it. One bad line should not cost you the rest.
Reference solution in Go
func orderTotal(lines []*Line) int {
total := 0
for _, l := range lines {
if l == nil || l.Qty <= 0 {
continue
}
total += l.Qty * l.UnitPrice
}
return total
}