Category: Intermediate

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Graph – Detect Cycle in an Undirected Graph using DFS

Objective: Given undirected graph write an algorithm to find out whether graph contains cycle or not. Example: Approach: Earlier we have seen how to find cycles in directed graphs. In this article we will...

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Graph – Detect Cycle in a Directed Graph

Objective: Given a directed graph write an algorithm to find out whether graph contains cycle or not. Example: Approach: Graph contains cycle if there are any back edges. There are two types of back...

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Topological Sort

Topological Sort: A topological sort or topological ordering of a directed graph is a linear ordering of its vertices such that for every directed edge uv from vertex u to vertex v, u comes before v in the ordering. A topological ordering is possible if and only if the graph has no directed...

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Print all sub sequences of a given String

Objec­tive:  Given a String write an algorithm to print all the possible sub subsequences. Example: String input = “abc”; Output: Possible sub sequences – {Empty}, {a}, {b}, {c}, {ab} ,{a,c}, {b, c}, {a, b, c}...

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Graph – Print all paths between source and destination

Objective: Given a graph, source vertex and destination vertex. Write an algorithm to print all possible paths between source and destination. This problem also known as “Print all paths between two nodes” Example: Approach:...

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Graph – Depth First Traversal

Objective – Given a graph, do the depth first traversal(DFS). What is depth-first traversal– Depth-first search (DFS) is an algorithm for traversing or searching tree or graph data structures. One starts at the root (selecting some arbitrary node as the root in the...

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Print all substrings of a given string

Objec­tive:  Given a string write an algorithm to print all the possible sub strings. Example: String input = “abcd”; Output: Possible sub strings – a          a b      a b c   a b c d b...

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Print all subarrays of a given array

Objec­tive:  Given an array write an algorithm to print all the possible sub arrays. Example: int [] a = {1, 2, 3}; Output: Possible subarrays – {1}, {2}, {3}, {1, 2} , {2, 3}, {1,...

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Divide and Conquer – Rearrange array elements in special order

Objec­tive:  Given an array of integers of size 2n, write an algorithm to arrange them such that first n elements and last n elements are set up in alternative manner. Say n = 3 and...

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Remove Duplicates from a string

Objective:  Given a string, write an algorithm to remove the duplicate characters in that string. Example: Input: tutorialhorizon Output: tuorialhzn Approaches: There are multiple approaches to solve this problem- Use Sorting – (Will change the...

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Find median of two sorted arrays of same size

Objective:  Given two sorted arrays of size n. Write an algorithm to find the median of combined array (merger of both the given arrays, size = 2n). What is Median? The median is the value separating the...

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Find local minimum or local maximum in O(1).

Objec­tive: Given an array such that every next element differs from the previous by +/- 1. (i.e. a[i+1] = a[i] +/-1 ) Find the local max OR min in O(1) time. The interviewer mentioned one...

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Majority Element- Boyer–Moore majority vote algorithm

Objec­tive:  Given an array of integer write an algorithm to find the majority element in it (if exist). Majority Element: If an element appears more than n/2 times in array where n is the size...

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