Salesforce Backend Engineer Interview Questions

Salesforce requires a robust messaging system for handling events and notifications processed by Business Applications.
Design a MessageQueue class that supports sending messages, receiving messages, and keeping track of pending messages.Example method signatures:
- void send(String message) - adds a message to the queue.
- String receive() - returns and removes the front message from the queue.
- boolean isEmpty() - checks if the queue is empty.Example 1:
Input: send("Update Customer")
Output: null
Explanation: Successfully sends the message.Constraints:
- 1 <= message.length() <= 250
- Queue should handle up to 10^5 messages efficiently.

Salesforce must manage API requests effectively to prevent abuse and ensure fair usage across all integrations.
Design a RateLimiter class to limit the number of requests a user can make within a specified time frame.Example method signatures:
- boolean allowRequest(String userId) - returns true if the request can be allowed, false otherwise.
- void resetRequests(String userId) - resets the request count for a user after their time window has expired.Example 1:
Input: userId = "user1", limit = 5, windowInSeconds = 60
Output: true
Explanation: No prior requests; hence the request is allowed.Constraints:
- 1 <= limit <= 100
- 1 <= windowInSeconds <= 3600.

Salesforce handles large volumes of marketing data and needs to analyze customer engagement over rolling time windows.
Given an array of integers representing daily engagement metrics, return the maximum sum of any k consecutive days.Example method signatures:
- int maxEngagement(int[] engagement, int k) - returns the maximum sum of engagement metrics over any k consecutive days.Example 1:
Input: engagement = [1, 2, 3, 4, 5], k = 3
Output: 12
Explanation: The maximum sum of any three consecutive days is 3 + 4 + 5 = 12.Constraints:
- 1 <= |engagement| <= 10^5
- 1 <= k <= |engagement|.

Salesforce needs to ensure efficient routing of customer service agents to the nearest issues, minimizing response time.
Given a graph represented by a Node class, identify the shortest path from a source to all other nodes using Dijkstra's algorithm.Example method signatures:
- List<Node> shortestPath(Node source) - returns a list of shortest paths from the source node to all other nodes.Example 1:
Input: source = Node A
Output: [Node B, Node C, Node D]
Explanation: The shortest path from A will include nodes B, C, and D based on edge weights.Constraints:
- 1 <= |nodes| <= 1000
- Each node has a unique identifier.