Chain inspection: Peak ticket
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Inputs
head is the first node of a linked list. In examples, [4, 7] means nodes 4 then 7, linked in that order. [] means no nodes. The runner builds the nodes for you.
Your tasks
- Create a list
values.headis the first node of a linked list. A node holds a number in val and a link to the next node in next. Follow next until there are no more nodes. Record each val in order. The list has no loops. An empty list gives an emptyvalues. - Find the largest number in
values. Store it inlargest. - Complete
chainInspectionPeakTicketso it returnslargest. Return it, do not print it.
Example
If head is [-4, 2, 12, 5, 2], then values is [-4, 2, 12, 5, 2] and chainInspectionPeakTicket returns 12.
Rules
- If
valuesis empty, return 0. - If every number is negative, return the largest negative number. Do not replace it with 0.
Test data
TEST DATA 1: head is [0, 14, 20, -7, 14].
TEST DATA 2: head is [7, 7, -7, 7].
Examples
Input: head = [0,14,20,-7,14] Output: 20
values is [0, 14, 20, -7, 14]. The largest number is 20. Return 20.
Input: head = [7,7,-7,7] Output: 7
values is [7, 7, -7, 7]. The largest number is 7. Return 7.
Input: head = [] Output: 0
values is []. The list is empty, so return 0.
Input limits
- 0 <= input size <= 50000.
- Answers fit in a signed 32-bit integer: -2,147,483,648 through 2,147,483,647.
- Input numbers have no decimal part. They range from -1,000,000 to 1,000,000. Follow any extra input rules in task 1.
- Linked lists do not loop back to an earlier node. Tree examples list nodes by level; null means a missing child. The runner builds the nodes shown in the examples.
Efficiency goal
Big-O describes how the work or memory needed grows as the input gets larger.
Efficiency goal: time O(n); extra memory, including the helper list, O(n). n is the number of nodes. These labels describe how work and memory grow with the input.
Practice focus
Build values first, then return exactly what the tasks ask for. Follow the order, keep repeated values when the rule says so, and check the empty case.