Print all middle elements of the given matrix/2D array.

Objective: Given a two-dimensional array, write a program to print all middle elements of the array. Or In other words, print all the elements from the array except boundary elements. Example: int [][] grid = new int[][] { {1, 2, 3, 4, 8}, {5, 6, 7, 8, 9}, {9, 8, 7, 6, 7}, {5, 4, … Read more Print all middle elements of the given matrix/2D array.

Find the number of distinct Islands OR connected components.

Objective: Given a 2d grid map of ‘1’s (land) and ‘0’s (water), count the number of distinct or unique islands. Island: An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. Assume all four edges of the grid are all surrounded by water. Given such a grid, write an … Read more Find the number of distinct Islands OR connected components.

Depth-First Search (DFS) in 2D Matrix/2D-Array – Recursive Solution

Objective: Given a two-dimensional array or matrix, Do the depth-First Search (DFS) to print the elements of the given matrix. Implement the Depth-first traversal in a recursive manner. Example: int [][] grid = new int[][] { {1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}} Output: Depth-First Traversal: … Read more Depth-First Search (DFS) in 2D Matrix/2D-Array – Recursive Solution

Breadth-First Search (BFS) in 2D Matrix/2D-Array

Objective: Given a two-dimensional array or matrix, Do the breadth-First Search (BFS) to print the elements of the given matrix. Implement a Breadth-first traversal in an iterative manner. Example: int [][] grid = new int[][] { {1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}} Output: Breadth-First Traversal: … Read more Breadth-First Search (BFS) in 2D Matrix/2D-Array

Number of Islands using BFS

Objective: Given a 2d grid map of ‘1’s (land) and ‘0’s (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. Assume all four edges of the grid are all surrounded by water. Given such grid, write an algorithm using Breadth-First Search(BFS) to … Read more Number of Islands using BFS

Depth-First Search (DFS) in 2D Matrix/2D-Array – Iterative Solution

Objective: Given a two-dimensional array or matrix, Do the depth-First Search (DFS) to print the elements of the given matrix. Implement the Depth-first traversal in an iterative manner. Example: int [][] grid = new int[][] { {1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}} Output: Depth-First Traversal: … Read more Depth-First Search (DFS) in 2D Matrix/2D-Array – Iterative Solution

Print Stack in reverse order.

Objective: Given a stack, write a program to print the stack elements in reverse order. Example: Approach: Use Temporary stack: Take temporary stack, and copy all the items from the given stack to a temporary stack. Elements will be stored in a temporary stack in reverse order. Now print elements from the temporary stack and … Read more Print Stack in reverse order.

Sort a given stack – Using Recursion

Objective: Given a stack of integers, write an algorithm to sort the stack using recursion.  Example: Original Stack: [14, 9, 67, 91, 101, 25] Sorted Stack: [9, 14, 25, 67, 91, 101] Original Stack: [4, 9, 6, 8, 10, 5] Sorted Stack is:[10, 9, 8, 6, 5, 4]  Approach: In this solution, we need two … Read more Sort a given stack – Using Recursion

Given an array, Print sum of all subsets

Objective: Given an array of numbers, write an algorithm to print all the subsets sum individually.   Example: Given Input: [1, 2] Output: 3 1 2 0 Explanation: subsets are [0], [1], [2], [1, 2] Given Input: [2, 4, 6] 12 6 8 2 10 4 6 0 Approach: Recursion Every element of the array has … Read more Given an array, Print sum of all subsets

Print all subsets of an array with a sum equal to zero

Objective: Given an array of integers write an algorithm to find all the subsets for which sum is equal to zero. The array contains both positive and negative integers. Example: Given Array: [8, 3, 5, 1, -4, -8], required sum: 0 Output: [-8, -4, 1, 3, 8] [-8, 3, 5] [-8, 8] [-4, 1, 3] … Read more Print all subsets of an array with a sum equal to zero

ZigZag OR Diagonal traversal in 2d array/Matrix using queue

Objective: Given a two-dimensional array or matrix, Write an algorithm to print the given matrix in a zigzag manner or in other words print all the diagonals of the matrix. Example: int [][] grid = new int[][] {            {1, 2, 3, 4},            {5, 6, 7, 8},            {9, 10, 11, 12},            {13, 14, 15, 16}} Output:  … Read more ZigZag OR Diagonal traversal in 2d array/Matrix using queue

Number of Islands

Objective: Given a 2d grid map of ‘1’s (land) and ‘0’s (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. Assume all four edges of the grid are all surrounded by water. Given such a grid, write an algorithm to find the … Read more Number of Islands

Evaluation of Postfix Expressions (Polish Postfix notation) | Set 2

Earlier we had discussed how to evaluate postfix expressions where operands are of single-digit. In this article, we will discuss how to evaluate postfix expressions for any number ( not necessarily single digit.) Postfix notation is a notation for writing arithmetic expressions in which the operands appear before their operators. Let’s assume the below Operands … Read more Evaluation of Postfix Expressions (Polish Postfix notation) | Set 2

Round Price Problem

Problem Statement: When customers book an Airbnb the total price, which includes base price + service fee + cleaning fee. all these prices are in decimals. Write an algorithm to round each price such that the sum of the prices equals the round of the total sum of all decimal prices and minimize the rounding. … Read more Round Price Problem