The second highest number
A leaderboard shows only the top name, but the report also wants the runner-up.
- Run the equal values together: 10, 10, 9 has a second largest of 9.
- Fewer than two distinct values gives -1.
secondLargest(values: list<int>) → 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 secondLargest(values []int) int {
}Worked examples
| Call | Result |
|---|---|
secondLargest([]int{3, 1, 2}) | 2 |
secondLargest([]int{10, 10, 9}) | 9 |
secondLargest([]int{4, 1, 4, 2, 3}) | 3 |
secondLargest([]int{5}) | -1 |
Hint
Walk once keeping the two best so far, and ignore a value equal to the current best.
Reference solution in Go
func secondLargest(values []int) int {
best, second := 0, 0
found, started := false, false
for _, v := range values {
if !started {
best = v
started = true
continue
}
if v > best {
second = best
found = true
best = v
} else if v < best {
if !found || v > second {
second = v
found = true
}
}
}
if found {
return second
}
return -1
}