Currency Exchange Rates | Dataford Interview Questions

Given a list of currency relationships with exchange values (e.g. BTC - USD), find the best exchange rate from currency1 to currency2.

Each relationship is directed: [source, destination, rate] means one unit of source becomes rate units of destination. Return the maximum product of rates along any simple path. Return 1.0 when both currencies are equal and 0.0 when the destination is unreachable. Asked in the coding round 1 stage. Edge cases like self loops expected.

Function: def best_exchange_rate(rates, currency1, currency2):

rates is a list of [string, string, float] values. Do not reuse a currency within one path.

Constraints

1 <= rates.length <= 1000
Each relationship has the form [source, destination, rate]
source and destination are non-empty strings
0 < rate <= 10^6
currency1 and currency2 are non-empty strings
A path may not visit the same currency more than once

Function Signature

def best_exchange_rate(rates, currency1, currency2):

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Problem