Coding questions · Supio

Compute max planes shot and session count

These questions evaluate algorithmic problem-solving skills: the first focuses on greedy scheduling and time-step simulation to maximize actions before deadlines while the second tests event aggregation, sorting and grouping logic for sessionization.

Problem 1: Max planes you can shoot before any lands

You are given two equal-length arrays:

altitude[i]: the initial altitude of plane i (positive integer)
descent[i]: the amount plane i descends per second (positive integer)

Time proceeds in whole seconds. At each second t = 0, 1, 2, ... you may shoot down at most one plane instantly (before it descends for that second). After your shot (or if you skip), all remaining planes descend by their descent value for that second.

A plane lands successfully if its altitude becomes <= 0 after descending at the end of some second.

If any plane lands, the process stops immediately.

Task: Assuming you choose the best possible plane to shoot each second, return the maximum number of planes you can shoot down before the first successful landing occurs.

Input: altitude[], descent[] (same length n)

Output: integer (max planes shot)

Problem 2: Count user sessions from events

You are given:

events: a list of pairs [userId, time] (times are integers; events may be in arbitrary order)
timeout: a non-negative integer

For each user, sort that user’s events by time. Two consecutive events for the same user belong to the same session if their time difference is <= timeout. Otherwise, the later event starts a new session.

Task: Return the total number of sessions across all users.

Input: events = [[userId, time], ...], timeout

Output: integer (number of sessions)

Maximum Planes Shot Before Landing

At each whole second t starting at 0, shoot at most one plane before remaining planes descend. Return the maximum number shot before any unshot plane lands.

Constraints

altitude and descent have the same length
All altitudes and descents are positive

Examples

Example 1

Input: ([1, 3, 4], [1, 1, 1])
Output: 3

Example 2

Input: ([1, 1, 2], [1, 1, 1])
Output: 1

Hints

Sort planes by their landing deadline ceil(altitude/descent).

Count User Sessions from Events

Group events by user, sort each user by time, and count a new session when the gap between consecutive events is greater than timeout.