nasneba

Nasneba Developer Pre-Test 2019

Question 1

Let p be the first input array and q be the second input array. This method constructs a bucket by iterating p then check the q existance by iterating q and check against with the bucket. Thus the running time is O(|p| + |q|)

Question 2

Cache is backed by HashMap. Cache.get(key) get the value and refresh its last access time if it is not null. Return -1 if it is null. HashMap.get(key) is constant time. CacheEntry.refresh() is constant time. return -1 is constant time. Therefore Cache.get(key) is O(1).

Question 3

Functions return by createArrayOfFunctions() would share the same i reference, causing those functions giving the same reuslt under the same input value x. This is closure features in javascript. Declare i using let instead of var would solve this issue since it will be limited in createArrayOfFunctions() local scope.

function createArrayOfFunctions(y) {
  var arr = [];
  for (let i = 0; i < y; i++) {
    arr[i] = function(x) {
      return x + i;
    }
  }
  return arr;
}

Question 4

Refer to src\main\java\com\nasneba\devtest\question4\Fibonacci.java