Technical Phone Interview

• The phone interview was 45 minutes long.
• I was asked to code this in Google Docs so I could not run my code

1. Technical Questions

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• What is deadlock
• What can you not do with a class with private constructor
• What is finally block
• How does hashmap work
• What should be a concerns when you are designing the hashmap
• Differnce between deep copy and shallow copy

2. Coding and Debugging Round

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1. Debug Hash function

What is wrong in the below code:

public override int GetHashCode(List<string> listA, bool isA){

		return IsA.GetHashCode()*31 + listA.GetHashCode();
}

2. Is the String Duplicate?

• Write a function to see if there is any duplicate character in the string.
• The string will contain only ascii characters.
• The function should have a time complexity of O(n) and space complexity of O(1).

3. What's Wrong in Parallel Computing

• ConcurrentDictionary is a Dictionary which is thread safe.

• DoCompute function is costly.

• What is wrong in the below code when multiple threads execute Compute function at the same time:

    ConcurrentDictionary<ComputeParams, double> _resultCache = new ConcurrentDictionary<ComputeParams, double>();
  
    public double Compute(ComputeParams params){
  
    	double result;
    	if (_resultCache.TryGetValue(params, out result)) return result;
    	var result = DoCompute(params);
    	_resultCache[params] = result;
    	return result;
    }
     
    double DoCompute(ComputeParams params){
  
    		// calculate
    }