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15,496 backend developer interview questions shared by candidates

Given the following code: class Asset { id: string; companyId: string; body: any; public equals(asset: Asset): boolean { return this.companyId == asset.companyId && this.id == asset.id; } } const diffUpdateAssets = (apiAssets: Asset[], dbAssets: Asset[]): Asset[] => { return apiAssets.filter( (asset: Asset) => dbAssets.find(asset.equals) ); }; const diffInsertAssets = (apiAssets: Asset[], dbAssets: Asset[], Map map): Asset[] => { return apiAssets.filter( (asset: Asset) => !dbAssets.find(asset.equals) ); }; const diffDeleteAssets = (apiAssets: Asset[], dbAssets: Asset[]): Asset[] => { return dbAssets.filter( (asset: Asset) => !apiAssets.find(asset.equals) ); }; export const syncAssets = (apiAssets: Asset[], dbAssets: Asset[]) => { return { toInsert: diffInsertAssets(apiAssets, dbAssets), toDelete: diffDeleteAssets(apiAssets, dbAssets), toUpdate: diffUpdateAssets(apiAssets, dbAssets), }; }; 1. Explain what the above code does. What's the time complexity of the code. How it can be improved? how this can be imporved. 2. Simple subquery / inner query SQL question, just learn sub queries. 3. Design question: All of our integrations in DoControl are based on webhooks notifications from the SaaS providers. In order to process those messages we perform a registration of our predefined POST webhook endpoint that will accept those events. Please plan a basic flow which will: a. Receive message from Google Drive b. Enrich its data with an api call performed per each event c. Insert the enriched record to a database.
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Senior Backend Engineer

Interviewed at DoControl

4.7★
Jun 5, 2023

Given the following code: class Asset { id: string; companyId: string; body: any; public equals(asset: Asset): boolean { return this.companyId == asset.companyId && this.id == asset.id; } } const diffUpdateAssets = (apiAssets: Asset[], dbAssets: Asset[]): Asset[] => { return apiAssets.filter( (asset: Asset) => dbAssets.find(asset.equals) ); }; const diffInsertAssets = (apiAssets: Asset[], dbAssets: Asset[], Map map): Asset[] => { return apiAssets.filter( (asset: Asset) => !dbAssets.find(asset.equals) ); }; const diffDeleteAssets = (apiAssets: Asset[], dbAssets: Asset[]): Asset[] => { return dbAssets.filter( (asset: Asset) => !apiAssets.find(asset.equals) ); }; export const syncAssets = (apiAssets: Asset[], dbAssets: Asset[]) => { return { toInsert: diffInsertAssets(apiAssets, dbAssets), toDelete: diffDeleteAssets(apiAssets, dbAssets), toUpdate: diffUpdateAssets(apiAssets, dbAssets), }; }; 1. Explain what the above code does. What's the time complexity of the code. How it can be improved? how this can be imporved. 2. Simple subquery / inner query SQL question, just learn sub queries. 3. Design question: All of our integrations in DoControl are based on webhooks notifications from the SaaS providers. In order to process those messages we perform a registration of our predefined POST webhook endpoint that will accept those events. Please plan a basic flow which will: a. Receive message from Google Drive b. Enrich its data with an api call performed per each event c. Insert the enriched record to a database.

Weigh several balls to find the heaviest in O(log n) time on a scale. This is worded so strangely that it may not be obvious at first what you're trying to solve. You're just trying to find the most efficient (least measurements) solution. "You have 9 balls that are identical but 1 weighs more than the others. Using a balance scale, how could you find the heavier ball efficiently, conserving the number of measurements?"
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Senior Backend Engineer

Interviewed at Facilities Management eXpress

3.7★
May 19, 2021

Weigh several balls to find the heaviest in O(log n) time on a scale. This is worded so strangely that it may not be obvious at first what you're trying to solve. You're just trying to find the most efficient (least measurements) solution. "You have 9 balls that are identical but 1 weighs more than the others. Using a balance scale, how could you find the heavier ball efficiently, conserving the number of measurements?"

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