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# Moonfrog Labs Interview Experience | Set 3

• Difficulty Level : Hard
• Last Updated : 15 Nov, 2015

Q1. Given a sequence of integers, find the longest increasing subsequence. Example:
arr = [1, 2, 5, 3, 7]
ans : [1, 2, 5, 7] or [1, 2, 3, 7]

arr = [4, 3, 1, 2]
ans: [1, 2].

Solution:

 `import` `java.util.Arrays;`` ` `/** @author hiccup  */``class` `LIS``{``    ``static` `int``[] maxLIS;``    ``static` `int``[] result;`` ` `    ``public` `static` `void` `getLCS(``int``[] arr)``    ``{``        ``if` `(``null` `== arr || ``0` `== arr.length)``            ``return``;`` ` `        ``maxLIS = ``new` `int``[arr.length];``        ``/* At least LCS is 1 i.e. element is the``                   ``only one in given sequence */``        ``Arrays.fill(maxLIS, ``1``);`` ` ` ` `        ``/**``         ``*``         ``*/``        ``for` `(``int` `curIdx = ``1``; curIdx < arr.length; curIdx++)``        ``{``            ``for` `(``int` `beginIdx = ``0``; beginIdx <= curIdx - ``1``; beginIdx++)``            ``{``                ``if` `(arr[curIdx] > arr[beginIdx])``                ``{``                    ``if` `(maxLIS[curIdx] < maxLIS[beginIdx] + ``1``)``                    ``{``                        ``//System.out.print(arr[curIdx] + "  ");``                        ``maxLIS[curIdx] = maxLIS[beginIdx] + ``1``;``                    ``}``                ``}``            ``}``        ``}`` ` `        ``int` `max = maxLIS[``0``];``        ``result = ``new` `int``[arr.length];``        ``Arrays.fill(result, -``1``);`` ` `        ``int` `cpIdx = ``0``;``        ``for` `(``int` `idx = ``0``; idx < maxLIS.length; idx++)``        ``{``            ``/* Put sequence at cpIdx   */``            ``if` `(-``1` `== result[maxLIS[idx] - ``1``])``            ``{``                ``result[cpIdx++] = arr[idx];``            ``}``        ``}`` ` `        ``/*  Print sequence       */``        ``for` `(``int` `idx = ``0``; idx < result.length; idx++)``        ``{``            ``System.out.print(result[idx] + ``" "``);``        ``}``    ``}`` ` `    ``public` `static` `void` `main(String[] args)``    ``{``        ``int``[] arr = {``1``, ``2``, ``5``, ``3``, ``7``};``        ``LIS.getLCS(arr);``    ``}``}`

[1, 2, 3, 3, 4]

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Q2. Given a vectors of numbers of fixed length, for example:

v1 = [4, 3, 1, 2] v2 = [2, 4, 3, 5]

The relationship nested between two vectors is defined as follows:

if the corresponding entries of a vector are all smaller than the other vector, after rearranging entries of vector if needed, then first vector
is said to be nested in the other. Example

Not nested
v1 – [4, 3, 1, 2] v2 – [2, 4, 3, 5]
v2 – [2, 4, 3, 5] v1 – [4, 3, 1, 2]

After re-arranging:

Nested
v1 – [4, 3, 1, 2]
v2 – [5, 4, 2, 3]

Hence v1 is nested in v2.

Given a pair of such vectors , write a function as follows:

function isNested(Vec a, Vec b);

Result:
-1 if a is nested in b
1 if b is nested in a
0 if nesting is not possible.

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Q3. Given a list of numbers in random order. Is it possible to pair all elements in the list in such a way that no two pairs share an element
and the sum of elements in a pair is divisible by 101. Example:

v1 [ 1, 100, 1]
Ans: No

v2 [1, 100, 100, 1] [2, 98, 101, 1]
Ans: Yes

v3 [1, 200, 100, 100, 2, 1]
Ans: yes

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