Freaks City

LeetCode 54: Spiral Matrix Problem Given an m x n matrix, return all elements of the matrix in spiral order. Example 1 Input: matrix = [[1,2,3],[4,5,6],[7,8,9]] Output: [1,2,3,6,9,8,7,4,5] Example 2 Input: matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]] Output: [1,2,3,4,8,12,11,10,9,5,6,7] Approach Traverse from left to right along the top r ...

A bracket string of even length consists of exactly n/2 opening [ and n/2 closing ] characters. The goal is to determine fewest number of arbitrary index swaps required to transform the string into a valid bracket sequence (one where every closing bracket has a matching opening bracket earlier in the string). Pairs of matched brackets can be t ...

283. Move Zeroes The objective is to reorganize an array such that all non-zero elements are positioned before any zeros. This operation must be performed in-place without allocating additional space for another array. Instead of using a secondary buffer, we can utilize a tracking pointer to mark the position where the next non-zero element sho ...

Problem Description We're playing a number guessing game with the following rules: I pick a number between 1 and n. You guess which number I picked. Each time you guess wrong, I tell you whether my number is higher or lower. When you guess a number x and it's wrong, you pay $x. You win when you guess the correct number. Given n ≥ 1, determine ...

This week's practice focuses on mastering binary search algorithms through LeetCode problems. The first problem is Binary Search. Below is the implementation: int search(int* nums, int numsSize, int target) { int left = 0; int right = numsSize - 1; while (left <= right) { int mid = left + (right - left) / 2; if ( ...

Stack Fundamentals A stack is a linear data structure that adheres to the Last-In, First-Out (LIFO) principle. This means the last element added to the stack is the first one to be removed. Operations on a stack are restricted to a single end, known as the top. The other end is called the bottom. Think of a stack like a stack of plates. You ...

Given a binary tree, we need to install cameras on its nodes. Each camera can monitor its parent, itself, and its immediate children. The goal is to determine the minimum number of cameras reuqired to cover the entire tree. Problem Constraints Number of nodes ranges from 1 to 1000. Node values are irrelevant (typically 0). Core Strategy The o ...

Minimum Path Sum in a Grid Finding the minimum path sum from the top-left to the bottom-right of a grid is a classic dynamic programming problem. To optimize space complexity, we can use a 1D array instead of a 2D matrix to store the DP states, updating the array iteratively as we traverse each row. #include <vector> #include <algorith ...

The Stocks table schema is defined as follows: Column Name Type stock_name varchar operation enum operation_day int price int The primary key for this table is the combination of stock_name and operation_day. The operation column is an enumeration containing ('Buy', 'Sell'). Each row represents a transaction made on a specific s ...

Given an integer array nums, find and return the maximum sum of elements that is divisible by three. Examples Example 1: Input: nums = [3,6,5,1,8] Output: 18 Explanation: Choose numbers 3, 6, 1, and 8. Their sum is 18 (the maximum sum divisible by three). Example 2: Input: nums = [4] Output: 0 Explanation: 4 is not divisible by 3, so no number ...