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Articles by Arnab Chakraborty
Page 68 of 377
Find the Celebrity in C++
Suppose we have n people (labeled from 0 to n - 1) and among them, there may exist one celebrity. We can say a person x is a celebrity when all the other n - 1 people know x but x does not know any of them. Here we have to find who the celebrity is or verify that there is not one.We are allowed to ask only one question to person ‘A’, that "Hi, A. Do you know B?" to get information of whether A knows B or not. We have to ask minimum number of questions tofind out ...
Read MoreProgram to find nth ugly number in C++
Suppose we have a number n; we have to find the nth ugly number. As we know that the ugly numbers are those numbers, whose prime factors are only 2, 3 and 5. So if we want to find 10th ugly number, the output will be 12, as the first few ugly numbers are 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 and so on.To solve this, we will follow these steps:Define an array v of size(n + 1)if n is same as 1, then:return 1two := 2, three := 3, five := 5twoIdx := 2, threeIdx := 2, fiveIdx := 2for initialize i := 2, when i
Read MoreProgram to check whether we can unlock all rooms or not in python
Suppose we have a list of lists called rooms. Each index i in rooms represents a room and rooms[i] represents different keys to open other rooms. The room 0 is open and we are at that room and every other room is locked. We can move freely between opened rooms; we have to check whether we can open every room or not.So, if the input is like rooms = [[2, 0], [3], [1], []], then the output will be True, as we start from room 0 and can go to room 2 with its key 2. From room 2 we ...
Read MoreZigzag Iterator in C++
Suppose there are two 1D arrays, we have to implement an iterator that will return their elements alternately. There will be two methods −next() − to get next elementhasNext() − to check whether the next element is present or not.So, if the input is like v1 = [1, 2] v2 = [3, 4, 5, 6] , then the output will be [1, 3, 2, 4, 5, 6], To solve this, we will follow these steps −Define one queue q of pairsFrom the initializer ake two arrays v1 and v2, if size of v1, then −insert { 0, 0 } into ...
Read MoreProgram to check whether a board is valid N queens solution or not in python
Suppose we have a n x n matrix represents a chess board. There are some 1s and 0s, where 1 represents a queen and 0 represents an empty cell. We have to check whether the board is valid solution to the N-Queen puzzle or not. As we know a board is a solution of valid N-queen solution where no two queens are attacking each other.So, if the input is likethen the output will be TrueTo solve this, we will follow these steps:n := row count of matrixrows := a new set, cols := a new set, diags := a new ...
Read MoreInorder Successor in BST in C++
Suppose we have a binary search tree and a node in it, we have to search the in-order successor of that node in the BST. As we know that the successor of a node p is the node with the smallest key greater than p.val.So, if the input is like root = [2, 1, 3], p = 1, then the output will be 2, To solve this, we will follow these steps −Define recursive method inorderSuccessor(), this will take root and pif root null, then −return nullif val of root val val){ return inorderSuccessor(root->right, p); ...
Read MoreProgram to find all possible strings typed using phone keypad in python
Suppose we have a string containing digits from 2-9. We have to find all possible letter combinations that the number could generate. One mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does map some characters but no letters.12a b c3d e f4g h i5j k l6m n o7p q r s8t u v9w x y z*0#For an example, if the given string is “49”, then the possible strings will be ['gw', 'gx', 'gy', 'gz', 'hw', 'hx', 'hy', 'hz', 'iw', 'ix', 'iy', 'iz']To solve this, we will follow these steps:Define an array ...
Read MoreProgram to remove sublist to get same number of elements below and above k in C++
Suppose we have a list of numbers called nums and another number k, we can remove any sublist at most once from the list. We have to find the length of the longest resulting list such that the amount of numbers strictly less than k and strictly larger than k is the same.So, if the input is like nums = [6, 10, 8, 9, 3, 5], k = 6, then the output will be 5, as if we remove the sublist [9] then we will get [6, 10, 8, 3, 5] and there are two numbers [3, 5] which are ...
Read MoreWalls and Gates in C++
Suppose we have one m x n 2D grid, and that is initialized with these three possible values.-1 for a wall or an obstacle.0 for a gate.INF This is infinity means an empty room.Here 2^31 - 1 = 2147483647 is INF as we may assume that the distance to a gate is less than 2147483647. Fill each empty room with the distance to its nearest gate. If it is impossible to reach a gate, it should be filled with INF.So, if the input is likeINF-10INFINFINFINF-1INF-1INF-10-1INFINFthen the output will be3-101221-11-12-10-134To solve this, we will follow these steps −Define an array dir ...
Read MoreProgram to find minimum number of days to wait to make profit in python
Suppose we have a list of prices representing the daily stock market prices of a company in chronological sequence. We have to find a same length list where the value at index i will be the minimum number of days we would have to wait until we make a profit. If there is no such way to make a profit the value should be 0.So, if the input is like prices = [4, 3, 5, 9, 7, 6], then the output will be [2, 1, 1, 0, 0, 0]To solve this, we will follow these steps:ans := a list of ...
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