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Question Write an algorithm to remove duplicated node from a linked list. Solution with O(n²) There are many ways to do it. For the first one, as the simplest one, we could use 2 loops to compare each element with all other elements. However, this takes forever: O(n²
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Question Validate a linked list whether there is a loop in it. That is, there is a node in a linked list with the next pointer pointing to a node ahead in the same linked list. This is the question I encountered in 2013 spring, from a Yahoo phone interview.
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Question Print a binary tree layer-by-layer from top to bottom, and from left to right for each layer. Solution Yes, it’s a simple task. We can use breadth-first search, and which means we need a queue. Example # node structure class bst_node: def __init__(self, value, left=None, right=
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Question Construct 2 algorithms to make mirror image of any binary tree inputs, one of them using recursive method, another one using looping method. Mirror image means a binary tree that is the horizontal reflection of the original tree. Solution First, to do it in recursive method, we can perform
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Question Given a sorted integer list and an integer, find two integer in the list such that the sum of the two integers equals the given integer. It is required that the time complexity must be O(n). For example, the sorted integer list is {1, 2, 4, 7, 11,
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Question Given a linked list, find the Kth last node in a linked list. The last 0th node is the tail node in the linked list. Solution Easy task. Construct 2 pointers: P1 and P2. First, both of them are set to head. Then move P2 to the next (K+
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Question Get the greatest distance between two nodes in a binary tree. Assume links between nodes are bidirectional. Distance is defined as the amount of nodes connected along the path linked two nodes. Write an algorithm to calculate distance between two nodes. Take the figure at the right, the greatest
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Question Simple task, reverse words in a sentence. Solution In Python, this can be simple because of the build-in functions. We can just split the sentence by spaces, reverse the list, and join them with spaces again. In C++, this can be complicated. The following might be one of the
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Question Construct an algorithm to verify if a set of numbers is the post-order search result of a binary search tree. Let the figure at the right hand side as an example, the algorithm will return true if {5, 7, 6, 9, 11, 10, 8}. However, it will return false
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Question Given 2 linked list head pointers, determine whether they intersect at some point. Solution First of all, linked list can have loop or not, and this gives 3 possible situations. 1. For the 2 loops head pointer 1 and head pointer 2, move pointer 1 at normal speed, and
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Question A self-descriptive number is an integer n in given base b is b digits long in which each digit at position p (the most significant digit being at position 0 and the least significant at position b – 1) counts how many times a digit p is in n. For
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Question Write an efficient program for printing k largest elements in an array. Elements in array can be in any order. For example, if given array is [1, 23, 12, 9, 30, 2, 50] and you are asked for the largest 3 elements i.e., k = 3 then your program