SLB Interview Experience — SWE New grad

At my university’s career fair, I found an opportunity with Schlumberger (SLB). They use a third-party service called KARAT for conducting their screening rounds.

KARAT Technical Round:

3 coding question + 3 MCQ were there and time limit was 50 minutes around :

MCQ : Don’t remember

Coding :

Suppose we have some input data describing a graph of relationships between parents and children over multiple generations. The data is formatted as a list of (parent, child) pairs, where each individual is assigned a unique positive integer identifier.

For example, in this diagram, 6 and 8 have common ancestors of 4 and 14.

               15
              / \
         14  13  21
         |   |
1   2    4   12
 \ /   / | \ /
  3   5  8  9
   \ / \     \
    6   7     11

pairs = [
    (1, 3), (2, 3), (3, 6), (5, 6), (5, 7), (4, 5),
    (15, 21), (4, 8), (4, 9), (9, 11), (14, 4), (13, 12),
    (12, 9), (15, 13)
]


1. Write a function that takes this data and the identifiers of two individuals 
as inputs and returns true if and only if they share at least one ancestor. 

Sample input and output:
hasCommonAncestor(pairs, 3, 8)   => false
hasCommonAncestor(pairs, 5, 8)   => true
hasCommonAncestor(pairs, 6, 8)   => true
hasCommonAncestor(pairs, 6, 9)   => true
hasCommonAncestor(pairs, 1, 3)   => false
hasCommonAncestor(pairs, 3, 1)   => false
hasCommonAncestor(pairs, 7, 11)  => true
hasCommonAncestor(pairs, 6, 5)   => true
hasCommonAncestor(pairs, 5, 6)   => true
hasCommonAncestor(pairs, 3, 6)   => true
hasCommonAncestor(pairs, 21, 11) => true

n: number of pairs in the input

2. Nodes with 1 parent and nodes with 0 parents.

Sample output: 
Node with 1 parent : 4, 13 , 21, 7, 11, 8, 5

Node with 0 parent : 1, 2, 14, 15


3. Earliest ancestor of a any given node.
 
Sample input and output:
EarliestAncestor( 8 )   => 14
EarliestAncestor( 14 )   => -1
EarliestAncestor( 6 )   => 14

Result : Ghosted