Playing with Pointers

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… Read More »

Unlocking the Enumeration/enum Mystery

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.… Read More »

Find the intersection points of 2 sorted arrays.

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… Read More »

The Stock Market Problem

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… Read More »

Longest substring without repeating characters

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… Read More »

Make a fair coin from a biased coin.

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.… Read More »

Find the left view of a binary tree.

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… Read More »

C cannot have static structure members

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 Table Implementations

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… Read More »

Symbol Tables

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… Read More »