Amazon Interview Question for Software Engineer / Developers


Country: United States
Interview Type: Phone Interview




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0
of 0 vote

In short:
Mergesort is a sorting algorithm that follows the paradigm of: divide and conquer:

1) recursivly split the array in 2
2) until the array length is 1 ( or the pointers start and end are equal)
3) merge the sorted array an return the array sorted

public static char[] mersort(char str[], int start, int end){
		if(str.length <= 1 ){
			return str;
		}else{

			int middle = (end-start)/2;
			char[] first_half = getArray(str,start,middle);
			char[] second_half = getArray(str,middle,end);
			char [] l1 = mersort(first_half,0,first_half.length);
			char [] l2 = mersort(second_half,0,second_half.length);
			return mergeArrays(l1,l2);
	}
	}

HashTable: Is an implementation of a Dictionary where you MAP Key and Values.
You need the Key's hashcode to located the bucket where the value is going to be store.
The hashcode must be well implemented shuch that It will always return the same value for the same key.
equals method should also be implemented in case of collision, so we can iterate over the list of values at the same bucket.

There are many implementation of MAP, one of them are hashtable which are thread safe. HashMap is similar but is not thread save.
There are other implementations where the key as store in oreder, so implemented the MapSorted such as treeMap.

hashtable operation runs on constant time O(1) (AVG), such as get, put, and contains.

There are many other things you can talk about hashing, like hashing functions, hashCode for Object class, and some others.

- .·´¯`·.´¯`·.¸¸.·´¯`·.¸><(((º> November 16, 2013 | Flag Reply
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of 0 vote

Stop posting incorrect answers on purpose @Anonymous

- varun sharma ( CEO of ms-amazon.blogspot.ca ) November 18, 2013 | Flag Reply
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-1
of 1 vote

Very common sde questions. Try it!

- unicorn November 16, 2013 | Flag Reply


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