Quant interview prep guides

Bridge and Torch Puzzle Interview Guide

Bridge and torch puzzle interview guide for constrained optimization, greedy traps, strategy comparison, proof, and communication.

Candidates practicing constrained optimization and case comparison.

Bridge puzzles are constrained schedules

Bridge-and-torch puzzles ask for an ordering that moves people across under speed and capacity constraints. The fastest individual is not always the only useful shuttle.

Compare strategy templates

The usual structure is to move slow people efficiently while using fast people to return the torch. Compare candidate schedules instead of trusting a greedy move.

Concrete example

When two slow people must cross, sending them together may be better than escorting each slow person separately, depending on the return costs.

Prove optimality lightly

After finding a schedule, explain why the slowest people require certain crossings or returns. A short lower-bound argument is stronger than only giving a number.

Common mistakes

Candidates often optimize one crossing at a time. The total plan matters because return trips can dominate the final time.

Practice the pattern

Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.