File: find-the-highest-altitude/solution.py

Date: 2026-06-06

Time: 16:46

find-the-highest-altitude/solution.py

Purpose

This file solves LeetCode 1732 — Find the Highest Altitude. It computes the maximum altitude reached by a biker who starts at altitude 0 and traverses a series of road segments, each with a net altitude gain (which can be negative). The gain array represents altitude *deltas* between consecutive checkpoints, not absolute altitudes.

Key Components

minoperations(gain: list[int]) -> int — Despite the misleading name (should be something like largestaltitude), this function computes a prefix-sum maximum. It takes a list of signed integers representing altitude changes between consecutive points and returns the highest altitude encountered along the trip.

Contract:

Patterns

Running accumulator with tracking max — a classic single-pass prefix-sum pattern. Instead of materializing the full prefix-sum array and calling max(), it maintains two scalars (alt for current altitude, max_alt for best seen), avoiding any extra allocation. This is the idiomatic O(n) time, O(1) space approach.

The if alt > maxalt check is equivalent to maxalt = max(max_alt, alt) but avoids a function-call overhead per iteration — a micro-optimization common in competitive programming solutions.

Dependencies

Imports: None. Pure computation with no library dependencies.

Imported by: The testsolution.py in the same directory, plus hundreds of other test files across the repo. The "Imported By" list in the prompt is misleading — those test files import their *own* solution modules, not this one. Only find-the-highest-altitude/testsolution.py actually imports this file.

Flow

1. Initialize max_alt and alt to 0 (biker starts at altitude 0)

2. For each gain value g, add it to the running altitude alt

3. If the new altitude exceeds maxalt, update maxalt

4. Return max_alt after processing all segments

Example: gain = [-5, 1, 5, 0, -7] produces altitudes [0, -5, -4, 1, 1, -6], so the answer is 1.

Invariants

Error Handling

None. The function assumes valid input per LeetCode constraints. An empty gain list returns 0 (the loop simply doesn't execute), which is correct — the biker stays at altitude 0.

Notable Issue

The function is named min_operations, which has no semantic connection to the problem. This is likely a copy-paste artifact from the code generation pipeline. It doesn't affect correctness but would confuse anyone reading the code without the module docstring.

Topics to Explore

Beliefs