Try it on GfG Practice Given an incomplete Sudoku in the form of matrix mat[][] of order 9*9, the task is to complete the Sudoku. A sudoku solution must satisfy all of the following rules: Each of the digits 1-9 must occur exactly once in each row.Each of the digits 1-9 must occur exactly once in…

Try it on GfG Practice Given a non-empty sequence s and a dictionary dict[] containing a list of non-empty words, the task is to return all possible ways to break the sentence in individual dictionary words. Note: The same word in the dictionary may be reused multiple times while breaking. Examples:…

Problem : A knight is placed on the first block of an empty board and, moving according to the rules of chess, must visit each square exactly once. Following is an example path followed by Knight to cover all the cells. The below grid represents a chessboard with 8 x 8 cells. Numbers in cells…

Try it on GfG Practice Given an integer n, the task is to find all distinct solutions to the n-queens problem, where n queens are placed on an n * n chessboard such that no two queens can attack each other. Note: Each solution is a unique configuration of n queens, represented as a permutation of…

Try it on GfG Practice Given a 2D matrix of dimension m✕n, the task is to print all the possible paths from the top left corner to the bottom right corner in a 2D matrix with the constraints that from each cell you can either move to right or down only. Examples : Input: [[1,2,3], [4,5,6]] Output:…

Given an array arr[] of size n, the task is to divide it into two subsets such that the absolute difference between the sum of elements in the two subsets. If n is even, both subsets must have exactly n/2 elements.If n is odd, one subset must have (n−1)/2 elements and the other must have (n+1)/2…

Try it on GfG Practice Given a path in the form of a rectangular matrix having few landmines arbitrarily placed (marked as 0), calculate length of the shortest safe route possible from any cell in the first column to any cell in the last column of the matrix. We have to avoid landmines and their…

Try it on GfG Practice Given a string, find all possible palindromic partitions of a given string. Note that this problem is different from Palindrome Partitioning Problem, there the task was to find the partitioning with minimum cuts in input string. Here we need to print all possible partitions.…

Try it on GfG Practice Given a set[] of non-negative integers and a value sum, the task is to print the subset of the given set whose sum is equal to the given sum. Examples: Input: set[] = {1,2,1}, sum = 3 Output: [1,2],[2,1] Explanation: There are subsets [1,2],[2,1] with sum 3. Input: set[] = {3,…

Try it on GfG Practice Given an M x N matrix, with a few hurdles arbitrarily placed, calculate the length of the longest possible route possible from source to a destination within the matrix. We are allowed to move to only adjacent cells which are not hurdles. The route cannot contain any diagonal…

Try it on GfG Practice Given an integer array arr[] and an integer k, the task is to check if it is possible to divide the given array into k non-empty subsets of equal sum such that every array element is part of a single subset. Examples: Input: arr[] = [2, 1, 4, 5, 6], k = 3 Output: true…

Try it on GfG Practice Given an undirected graph represented by the edgeList[][], where each edgeList[i] contains three integers [u, v, w], representing an undirected edge from u to v, having distance w. You are also given a source vertex, and a positive integer k. Your task is to determine if there…

Try it on GfG Practice Trapping Rainwater Problem states that given an array of n non-negative integers arr[] representing an elevation map where the width of each bar is 1, compute how much water it can trap after rain. Trapping Rainwater Problem Examples: Input: arr[] = [3, 0, 1, 0, 4, 0, 2]…

Given a weighted, directed graph G, an array V[] consisting of vertices, the task is to find the Minimum Cost Path passing through all the vertices of the set V, from a given source S to a destination D. Examples: Input: V = {7}, S = 0, D = 6 Output: 11 Explanation: Minimum path 0->7->5->6.…

Given a stack St of M elements and a queue Q of N elements. The task is to put every element of stack into the queue and every element of the queue into the stack without changing their order. Examples: Input: St = {4, 3, 2, 1}, Q = {8, 7, 6, 5} Output: St = {8, 7, 6, 5}, Q = {1, 2, 3, 4} Input: St…

What is Queue? Queue is an abstract data type that is open at both ends. One end is always used to insert data (enqueue) which is basically the rear/back/tail end and the other which is the front end is used to remove data (dequeue). Queue follows First-In-First-Out (FIFO) methodology, i.e., "the…

Given a directed weighted graph consisting of N vertices and an array Edges[][], with each row representing two vertices connected by an edge and the weight of that edge, the task is to find the path with the maximum sum of weights from a given source vertex src to a given destination vertex dst,…

Given a Directed Graph and two vertices src and dest, check whether there is a path from src to dest. Example: Consider the following Graph: adj[][] = [ [], [0, 2], [0, 3], [], [2] ] Input : src = 1, dest = 3 Output: Yes Explanation: There is a path from 1 to 3, 1 -> 2 -> 3 Input : src = 0, dest = 3…

Design a data structure for LRU Cache. It should support the following operations: get and put. get(key) - Returns the value of the given key if it exists in the cache; otherwise, returns -1.put(key, value) - Inserts or updates the key-value pair in the cache. If the cache reaches capacity, remove…

Try it on GfG Practice Given an input stream s consisting solely of lowercase letters, you are required to identify which character has appeared only once in the stream up to each point. If there are multiple characters that have appeared only once, return the one that first appeared. If no…

Try it on GfG Practice There are n gas stations along a circular tour, where the amount of gas at the ith gas station is gas[i]. You have a car with a gas tank of unlimited capacity and it costs cost[i] of gas to travel from the ith station to its next station. You begin the journey with an empty…

Try it on GfG Practice Geek is in a maze of size N * M. Each cell in the maze is made of either '.' or '#'. An empty cell is represented by '.' and an obstacle is represented by '#'. The task is to find out how many different empty cells he can pass through If Geek starts at cell (R, C) and avoids…

Given a stream of characters and we have to find first non repeating character each time a character is inserted to the stream. Examples: Input : a a b c Output : a -1 b b Input : a a c Output : a -1 c Recommended Practice First non-repeating character in a stream Try It! We have already discussed a…

Try it on GfG Practice Given a square chessboard of n x n size, the position of the Knight and the position of a target are given. We need to find out the minimum steps a Knight will take to reach the target position. Examples: Input: Knight knightPosition: (1, 3) , targetPosition: (5, 0) Output: 3…

Given an n x m grid of 'W' (Water) and 'L' (Land), the task is to count the number of islands. An island is a group of adjacent 'L' cells connected horizontally, vertically, or diagonally, and it is surrounded by water or the grid boundary. The goal is to determine how many distinct islands exist in…

Try it on GfG Practice Given a binary tree and the task is to find the spiral order traversal of the tree and return the list containing the elements. Spiral order Traversal: Starting from level 0 for root node, for all the even levels we print the node's value from right to left and for all the odd…

Try it on GfG Practice Given an array and a positive integer k, find the first negative integer for each window(contiguous subarray) of size k. If a window does not contain a negative integer, then print 0 for that window. Examples: Input: arr[] = [-8, 2, 3, -6, 1] , k = 2 Output: [-8, 0, -6, -6]…

Try it on GfG Practice Given a Binary tree and a key in the binary tree, find the node right to the given key. If there is no node on right side, then return NULL. Expected time complexity is O(n) where n is the number of nodes in the given binary tree. Example: Input: root = [10 2 6 8 4 N 5] and…

Try it on GfG Practice Given an undirected graph, the task is to determine if cycle is present in it or not. Examples: Input: V = 5, edges[][] = [[0, 1], [0, 2], [0, 3], [1, 2], [3, 4]] Undirected Graph with 5 Node Output: true Explanation: The diagram clearly shows a cycle 0 → 2 → 1 → 0. Input: V =…

Deque also known as double ended queue, as name suggests is a special kind of queue in which insertions and deletions can be done at the last as well as at the beginning. A link-list representation of deque is such that each node points to the next node as well as the previous node. So that…

Implement Priority Queue using Linked Lists. The Linked List should be so created so that the highest priority ( priority is assigned from 0 to n-1 where n is the number of elements, where 0 means the highest priority and n-1 being the least ) element is always at the head of the list. The list is…

Try it on GfG Practice Given a number n, write a function that generates and prints all binary numbers with decimal values from 1 to n. Examples: Input: n = 2 Output: 1, 10 Explanation: The first two non-zero numbers with digits as 0 and 1 only Input: n = 5 Output: 1, 10, 11, 100, 101 [Simple…

Try it on GfG Practice Given a stack that supports push and pop operations, your task is to implement a queue using one or more instances of that stack along with its operations. Table of Content By Making Enqueue Operation Costly A queue can be implemented using two stacks. Let the queue be…

Try it on GfG Practice Implement a stack using queues. The stack should support the following operations: Push(x): Push an element onto the stack.Pop(): Pop the element from the top of the stack and return it. A Stack can be implemented using two queues. Let Stack to be implemented be 's' and queues…

Given a Queue consisting of first n natural numbers (in random order). The task is to check whether the given Queue elements can be arranged in increasing order in another Queue using a stack. The operation allowed are: Push and pop elements from the stack Pop (Or Dequeue) from the given Queue. Push…

Problem: Design a Data Structure a SpecialQueue which supports following operations enqueue, deque, getMin() or getMax() where getMin() operation takes O(1) time. Example: Let the data to be inserted in queue be - 4, 2, 1, 6Operation Queue Output push(4) 4 - push(2) 4, 2 - push(1) 4, 2, 1 - getMin()…

Deque or Double Ended Queue is a generalized version of the Queue data structure that allows insert and delete at both ends. Operations on Deque: Mainly the following four basic operations are performed on queue: insertFront(): Adds an item at the front of Deque.insertRear(): Adds an item at the…

Try it on GfG Practice Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. For example, minimum depth of below Binary Tree is 2. Note that the path must end on a leaf node. For example, the…

Try it on GfG Practice Given an integer k and a queue of integers, The task is to reverse the order of the first k elements of the queue, leaving the other elements in the same relative order. Only following standard operations are allowed on the queue. enqueue(x): Add an item x to rear of…

Try it on GfG Practice Given a Binary Tree, the task is to print the nodes level-wise, each level on a new line. Example: Input: Output: 1 2 3 4 5 Table of Content [Naive Approach] - Using Recursion - O(n^2) Time and O(n) Space A simple solution to perform level order traversal is to first calculate…