Saturday, April 13, 2013

interview question answers continued

Q: How do you update the game of a black and white coin game such as Othello ?
A: In the update mode, find the longest sequence of the coin opposite of the color to be played. If this sequence has options to be bounded, place the coins at one of the ends. Choice of ends can be based on the side that has odd number of open spaces. The set of sequence can be based on the state of the game. and can generally be identified by expanding out from the center.

 Q: Given the root of a binary search tree along with a node inside it, find the successor node for the given node.
A: The structure of a binary search tree lets us determine the successor of a node without ever comparing keys. If the right subtree of node x is non-empty, then the successor of x is the leftmost node of the right subtree.If the right subtree of node x is empty and x has a successor y, then y is the lowest ancestor of x whose left child is also an ancestor of x.

Q: Given a lot of intervals [ai, bi], you have to find  a point with the intersection of most number of intervals.
A: We can maintain a count of inclusions in intervals for each point as we traverse the numberline from the minimum ai to the maximum bi.

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