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
Java 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
int secondLargest(List<Integer> values) {
}Worked examples
| Call | Result |
|---|---|
secondLargest(Main.<Integer>ls(3, 1, 2)) | 2 |
secondLargest(Main.<Integer>ls(10, 10, 9)) | 9 |
secondLargest(Main.<Integer>ls(4, 1, 4, 2, 3)) | 3 |
secondLargest(Main.<Integer>ls(5)) | -1 |
Hint
Walk once keeping the two best so far, and ignore a value equal to the current best.
Reference solution in Java
int secondLargest(List<Integer> values) {
int best = 0, second = 0;
boolean found = false, started = false;
for (int v : 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; }
}
}
return found ? second : -1;
}