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Articles by Nizamuddin Siddiqui
Page 8 of 196
What is the difference between Last() and LastOrDefault() in Linq C#?
Both Last() and LastOrDefault() are LINQ extension methods that retrieve the last element from a sequence. The key difference is how they handle empty sequences or no matching elements: Last() throws an InvalidOperationException when no element is found, while LastOrDefault() returns the default value for the type (null for reference types, 0 for integers, etc.). Syntax Following is the syntax for Last() method − public static T Last(this IEnumerable source); public static T Last(this IEnumerable source, Func predicate); Following is the syntax for LastOrDefault() method − public static T LastOrDefault(this IEnumerable source); ...
Read MoreHow to sort 0,1,2 in an Array (Dutch National Flag) without extra space using C#?
The Dutch National Flag problem is a classic algorithm challenge that sorts an array containing only 0s, 1s, and 2s in a single pass without using extra space. This problem was originally described by Dutch computer scientist Edsger Dijkstra and is also known as the Three-Way Partitioning algorithm. The algorithm uses three pointers to partition the array into three regions: all 0s on the left, all 1s in the middle, and all 2s on the right. Algorithm Overview The algorithm maintains three pointers − low − Points to the boundary of the 0s region mid ...
Read MoreHow to rotate an array k time using C#?
Array rotation is a common programming problem where elements are shifted by k positions. When we rotate an array to the right by k positions, the last k elements move to the beginning, and the remaining elements shift right. For example, if we have array [1, 2, 3, 4, 5] and rotate it right by 2 positions, we get [4, 5, 1, 2, 3]. Algorithm The most efficient approach uses the reversal algorithm which works in three steps − Reverse the entire array Reverse the first k elements Reverse the remaining elements from position k ...
Read MoreHow to return the index of first unique character without inbuilt functions using C#?
Finding the index of the first unique character in a string is a common programming problem. The approach involves using a frequency array to count character occurrences, then traversing the string again to find the first character with a count of 1. The algorithm uses an array of size 256 to accommodate all ASCII characters. First, we count the frequency of each character, then we find the first character that appears exactly once. Algorithm Steps The solution follows these steps − Create an integer array of size 256 to store character frequencies ...
Read MoreWhat are the different ways to find missing numbers in a sorted array without any inbuilt functions using C#?
Finding missing numbers in a sorted array is a common programming problem with multiple efficient solutions. This article explores three different approaches to identify missing numbers without using built-in functions in C#. Each method has its own advantages in terms of time and space complexity, making them suitable for different scenarios depending on your specific requirements. Using Sum Formula (Mathematical Approach) This method uses the mathematical formula n(n+1)/2 to calculate the expected sum of consecutive numbers, then subtracts the actual sum of array elements to find the missing number − using System; public class ...
Read MoreHow to find the missing number and the repeated number in a sorted array without using any inbuilt functions using C#?
Finding the missing number and the repeated number in a sorted array is a common programming problem. This article demonstrates how to solve this problem without using any built-in functions in C#. The approach uses a boolean array to track which numbers are present and an integer array to count occurrences. By traversing the original array and marking elements in auxiliary arrays, we can identify both the missing and repeated elements efficiently. Algorithm Overview The solution works in two main steps − Finding the missing number: Create a boolean array and mark elements as ...
Read MoreHow to find the minimum number of jumps required to reach the end of the array using C#?
The minimum number of jumps problem involves finding the least number of jumps required to reach the end of an array, where each element represents the maximum number of positions you can jump forward from that index. Given an array where each element represents the maximum jump length from that position, we need to find the minimum jumps to reach the last index. For example, in array {1, 3, 6, 3, 2, 3, 6, 8, 9, 5}, we can reach the end in 4 jumps. Jump Path Visualization 1 ...
Read MoreHow to rotate a matrix of size n*n to 90-degree k times using C#?
Rotating a matrix by 90 degrees is a common operation in programming. When we need to rotate a matrix k times, we can optimize by noting that 4 rotations return the matrix to its original state. Therefore, we only need to perform k % 4 rotations. The algorithm works by processing concentric squares within the matrix. For an n×n matrix, there are n/2 concentric squares. In each square, elements move in a cycle of 4 positions during a 90-degree clockwise rotation. 90° Clockwise Rotation Pattern Original ...
Read MoreHow to print a matrix of size n*n in spiral order using C#?
Printing a matrix in spiral order means traversing the matrix elements layer by layer from the outermost to the innermost layer. We start from the top-left corner and move in a clockwise direction: right, down, left, and up, then repeat for the inner layers. Algorithm Steps Step 1 − Print all elements of the top row from left to right Step 2 − Print all elements of the rightmost column from top to bottom Step 3 − Print all elements of the bottom row from right to left Step 4 − Print all elements of the leftmost ...
Read MoreHow to print number of islands in a given matrix using C#?
An island in a matrix is a group of connected cells containing '1' (representing land) that are surrounded by '0' (representing water). Two cells are considered connected if they are adjacent horizontally or vertically. This problem uses Depth-First Search (DFS) to traverse and mark all connected land cells as visited. The algorithm performs a linear scan of the 2D grid. When it finds a '1' that hasn't been visited, it triggers a DFS to explore the entire connected island and marks all cells in that island as visited. Each DFS call represents one complete island. Algorithm Steps ...
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