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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] Algorithm To solve this problem, we will ... Read More
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 ? 1 2a b c 3d e f 4g h i 5j k l 6m n o 7p q r s 8t u v 9w x y z * 0 # For example, if the given string is "49", then the possible strings will be ['gw', 'gx', 'gy', 'gz', ... Read More
The N-Queens puzzle is a classic problem where we need to place N queens on an N×N chessboard such that no two queens attack each other. In this article, we'll learn how to verify whether a given board configuration is a valid N-Queens solution. A valid N-Queens solution must satisfy these conditions: Exactly N queens are placed on the board No two queens share the same row, column, or diagonal Understanding the Problem Given an N×N matrix with 1s representing queens and 0s representing empty cells, we need to check if it's a valid N-Queens ... Read More
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. Room 0 is open and we start there, while every other room is locked. We can move freely between opened rooms — we need 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. We start from room 0 and can go to room 2 with its key 2. From room 2 we can ... Read More
Suppose we have a list of numbers called nums representing the height of square blocks. We need to check whether the shape is symmetric over the y = x line (diagonal reflection). For a shape to be symmetric over the y = x line, when we reflect it diagonally, the resulting shape should be identical to the original. Problem Understanding Given nums = [7, 5, 3, 2, 2, 1, 1], we need to verify if this block arrangement is symmetric over the y = x line. ... Read More
Suppose we have a linked list. We have to sort the list into ascending order using Python. So, if the input is like [5, 8, 4, 1, 5, 6, 3], then the output will be [1, 3, 4, 5, 5, 6, 8] Algorithm To solve this, we will follow these steps − Extract all values from the linked list into a Python list Sort the extracted values using built-in sort() method Traverse the original linked list again and replace node values with sorted ... Read More
Suppose we have a list of numbers called items and another value n. A salesman has items in a bag with random IDs. The salesman can remove as many as n items from the bag. We have to find the minimum number of different IDs remaining in the bag after n removals. The strategy is to remove items with the lowest frequencies first, as this minimizes the number of different IDs left. Example If the input is like items = [2, 2, 6, 6] and n = 2, then the output will be 1. We can sell ... Read More
In this problem, we need to check whether two binary trees have the same sequence of leaf nodes when read from left to right. A leaf node is a node that has no left or right children. So, if the input trees are: Tree 1 1 3 2 6 ... Read More
Sometimes we need to reverse words in a string while keeping delimiters in their original positions. This is useful when processing formatted text where the structure must be preserved but the word order needs to be reversed. So, if the input is like s = "Computer/Network:Internet|tutorialspoint" with delimiters ["/", ":", "|"], then the output will be tutorialspoint/Internet:Network|Computer. Algorithm To solve this problem, we follow these steps ? Extract all words (non-delimiter characters) and store them in a list Iterate through the original string character by character If the character is a delimiter, add it directly ... Read More
Given a linked list and two positions i and j, we need to reverse the nodes from position i to position j (0-indexed). The rest of the nodes remain in their original positions. For example, if we have a linked list [1, 2, 3, 4, 5, 6, 7, 8, 9] with i = 2 and j = 6, the output will be [1, 2, 7, 6, 5, 4, 3, 8, 9]. Algorithm To solve this problem, we follow these steps: Create a dummy head node pointing to the original head Traverse to find the node ... Read More