Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Economics & Finance
Suppose we have a binary tree, we have to find the most frequent subtree sum. The subtree sum of a node is the sum of all values under a node, including the node itself. So, if the input is like -6 3 6 Subtree sums: 3, 6, 3 (-6+3+6) then the output will be 3 as it occurs twice — ... Read More
Given a list of numbers and a value k, we need to find the number of non-empty subsets where the sum of minimum and maximum elements is less than or equal to k. Note that subsets are treated as multisets, meaning duplicate values can appear since they refer to specific positions in the list. For example, if nums = [2, 2, 5, 6] and k = 7, the valid subsets are: [2], [2], [2, 2], [2, 5], [2, 5], [2, 2, 5], giving us 6 subsets total. Algorithm The approach uses a two-pointer technique after sorting the ... Read More
Suppose we have a matrix of tasks where each row has 3 values representing costs for different resources. We also have another value k. We need to select k rows from tasks to minimize the total cost, which is calculated as the sum of maximum values from each of the 3 columns in the selected rows. The cost formula is: max(column_0) + max(column_1) + max(column_2) from the k selected rows. Problem Example If the input is like tasks = [[2, 3, 3], [4, 5, 2], [4, 2, 3]] and k = 2, then the output will be ... Read More
Suppose we have a list of numbers called nums, and we can perform an operation to update any element to any value. We can perform at most 3 such operations, and we need to find the resulting minimum difference between the max and min values in nums. So, if the input is like nums = [2, 3, 4, 5, 6, 7], then the output will be 2. We can change the list to [4, 3, 4, 5, 4, 4] and then 5 - 3 = 2. Algorithm To solve this problem, we follow these steps − ... Read More
Sometimes we need to find the smallest possible difference between any element from one list and any element from another list. Python provides an efficient solution using the two-pointer technique after sorting both lists. So, if the input is like L1 = [2, 7, 4], L2 = [16, 10, 11], then the output will be 3, as the smallest difference is 10 - 7 = 3. Algorithm Steps To solve this efficiently, we will follow these steps ? Sort both lists L1 and L2 Initialize minimum difference as infinity ... Read More
Suppose we have a list containing 0s and 1s, we have to remove values from the front or from the back of the list. Finally, we have to find the minimum number of deletions required such that the remaining list has an equal number of 0s and 1s. So, if the input is like nums = [1, 1, 1, 0, 0, 1], then the output will be 2, as we can delete the first one 1 and last one 1 so that there's two 1s and two 0s. Algorithm To solve this, we will follow these steps ... Read More
Given a list of lowercase alphabetical strings, we need to find the maximum sum of lengths of two distinct words that do not share any common letters. This problem can be efficiently solved using bit manipulation to represent character sets. Problem Understanding For the input words = ["abcd", "mno", "abdcmno", "amno"], we need to find two words with no common letters. The words "abcd" and "mno" share no common letters, giving us a total length of 4 + 3 = 7. Algorithm Approach We use bit manipulation where each bit position represents a letter (a=0, b=1, ... Read More
Finding the maximum sum of non-adjacent nodes in a binary tree is a classic dynamic programming problem. We need to select nodes such that no parent-child pairs are included, maximizing the total sum. Problem Understanding Given a binary tree, we want to find the maximum sum where no two selected nodes are adjacent (parent-child relationship). For each node, we have two choices: include it or exclude it. 1 2 10 ... Read More
Suppose we have two lists A and B of the same length, and a 2D list C containing pairs [i, j] that allow us to swap elements A[i] and A[j] as many times as needed. We need to find the maximum number of equivalent pairs where A[i] = B[i] after optimal swapping. The key insight is that elements connected through swap operations form groups, and within each group, we can arrange elements in any order to maximize matches. Example If the input is A = [5, 6, 7, 8], B = [6, 5, 8, 7], and C ... Read More
This problem requires finding the maximum possible minimum value in an array after performing K operations. Each operation increments a contiguous subarray of specified size by 1. We use binary search combined with a greedy approach to solve this efficiently. Problem Understanding Given an array nums, we can perform K operations where each operation: Selects a contiguous subarray of length size Increments every element in that subarray by 1 Our goal is to maximize the minimum value in the final array. Example Walkthrough For nums = [2, 5, 2, 2, 7], size = ... Read More