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Question: What is a Pointer? What are its limitations? What are its benefits? How do we use it? What all operation we can perform using it? In this article we are going to discover answers to all these questions. Pointer is a variable that contain the address of another variable and that variable can be a structure, array or basic data type. The basic syntax to define the pointer is as follows: Datatype * identifier; Datatype is the data type of the variable whose address we are going to store…

What are enums actually? Enums provide an opportunity to the user to define a shorthand for fixed set of constants like months in a year, gender etc. Enumeration is the list of constant integer values, which means that the enum values can’t be modified. Here we are going to explain Enumeration usage rules and constraints in C language. In C Enums are defined by enum keyword. The enum definition is analogous to the way a structure is defined . Syntax: tagname – It is the name given to the enum…

Question: Given 2 sorted arrays, find the intersection elements between them. Array 1: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26 Array 2: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33 Output: 6, 12, 18, 24 Let’s called Array1 as “A” and Array2 as “B”, each with size m and n. The obvious brute-force solution is to scan through each element in A, and for each element in A, scan if that element exist in B. The running time complexity is O(m*n).…

Question: Let us suppose we have an array whose ith element gives the price of a share on the day i. If you were only permitted to buy one share of the stock and sell one share of the stock, design an algorithm to find the best times to buy and sell. When we talk about the best times to sell and buy, we mean that we want the best profit possible. A profit is possible when our buying rate is less than the selling rate. We need to maximize…

Question: Given a string, find the length of the longest substring without repeating characters. Input: “abcabcbb” Output: “abc” Input: “bbbb” Output: “b” The longest substring without repeating letters for “abcabcbb” is “abc”, which the length is 3. For “bbbbb” the longest substring is “b”, with the length of 1. We definitely have the brute-force method, where we find each string and then compare. But we want to speed up the process. How can we can look up if a character had existed in the substring instantaneously? The answer is using…

Question: You are given a function foo() that represents a biased coin. When foo() is called, it returns 0 with 60% probability, and 1 with 40% probability. Write a new function that returns 0 and 1 with 50% probability each. Your function should use only foo(), no other library method. We know foo() returns 0 with 60% probability. How can we ensure that 0 and 1 are returned with 50% probability? If we can somehow get two cases with equal probability, then we are done. We call foo() two times.…

Question: Given the root pointer to a binary tree, find the left view of the tree. Input: Sample Tree (Pointer to node 1 is given). Output: 1, 2, 4 At a single glance of the problem, we can understand that we need to perform a level order traversal on the tree. This is similar to finding the number of levels in a tree. At the start of each level, we just print the first element. This can be done with the algorithm below:- Time Complexity:- O(n) Space Complexity:- O(n) Ideone…

In C, a structure cannot have static members, but in C++ a structure can have static members. For example, following program causes compilation error in C, but works in C++. Feel free to add your opinion.

Symbol Tables can be implemented in many ways and here are some of them. Unordered Array Implementation With this method, just maintaining an array is enough. It needs O(n) time for searching, insertion and deletion in the worst case. Ordered [Sorted] Array Implementation In this we maintain a sorted array of keys and values. Store in sorted order by key keys[i] = ith largest key values[i] = value associated with ith largest key Since the elements are sorted and stored in arrays, we can use simple binary search for finding…

Since childhood, we have all used a dictionary, and many of us have used a word processor (say Microsoft WORD) which comes with a spell checker. The spell checker is also a dictionary but limited. There are many real time examples for dictionaries and few of them are:- Spelling checker The data dictionary found in database management applications Symbol tables generated by loaders, assemblers, and compilers Routing tables in networking companies (DNS Lookup) In computer science, we generally use the term symbol table rather than dictionary, when referring to the…