LeetCode is an online platform that provides a vast collection of programming challenges to prepare programmers for technical interviews. It covers various topics, including data structures, algorithms, and database management systems.

## Busy intersection leetcode:

The **Busy Intersection LeetCode** problem is a typical optimization problem that requires a deep understanding of algorithms and data structures. It is often used as an interview question by companies that deal with traffic management and transportation systems.

Busy Intersection LeetCode is a programming challenge that simulates a busy intersection with multiple traffic lights. The problem requires developing an algorithm to determine the optimal traffic light sequence to minimize the waiting time for all cars passing through the intersection. This problem is similar to real-world traffic management, where traffic lights are controlled based on traffic flow and density to ensure smooth traffic flow.

The solution to the Busy Intersection LeetCode problem involves using a priority queue to store the next traffic light to turn green. The priority queue is sorted based on the time it takes for the traffic light to turn green, with the traffic lights with the shortest wait time having the highest priority. The algorithm then processes each car and determines the optimal time to start moving, given the current state of the traffic lights.

One important consideration when solving the Busy Intersection LeetCode problem is the potential for deadlock, where multiple cars are stuck at the intersection waiting for a green light. To avoid this, the algorithm must be designed to ensure that every car can pass through the intersection eventually.

In this article, we will explore the 20 most interesting LeetCode questions answered so far.

## Two Sum:

Two Sums is one of the most basic and frequently asked problems on LeetCode. The problem asks to find two numbers in an array that add up to a given target. The solution is straightforward and involves using a hash table to store the complement of each number.

## Longest Substring without Repeating Characters:

The problem requires finding the length of the longest substring without repeating characters. The solution involves using a sliding window technique and a hash table to keep track of the last occurrence of each character.

## Median of Two Sorted Arrays:

The problem asks to find the median of two sorted arrays. The solution involves finding the middle element of the merged array, and it requires binary search.

## Container with Most Water:

The problem asks to find the container with the most water given an array of heights. The solution involves using two pointers to scan the array and calculate the area of the container.

## Reverse Integer:

The problem requires reversing an integer. The solution involves using modulo and division operations to extract each digit and construct the reversed integer.

## Palindrome Number:

The problem asks to check if a given number is a palindrome. The solution involves reversing the number and comparing it with the original number.

## Merge Intervals:

The problem requires merging overlapping intervals. The solution involves sorting the intervals and merging them using two pointers.

## Swap Nodes in Pairs:

The problem requires swapping every two adjacent nodes in a linked list. The solution involves using recursion and pointer manipulation.

## Letter Combinations of a Phone Number:

The problem requires generating all possible letter combinations given a phone number. The solution involves using a backtracking algorithm.

## Longest Valid Parentheses:

The problem requires finding the length of the longest valid parentheses substring in a string. The solution involves using a stack and dynamic programming.

## Unique Paths:

The problem requires finding the number of unique paths from the top-left corner to the bottom-right corner of a grid. The solution involves using dynamic programming.

## Word Search:

The problem requires finding if a word exists in a 2D grid of characters. The solution involves using backtracking and DFS.

## Generate Parentheses:

The problem requires generating all possible valid parentheses combinations of a given length. The solution involves using backtracking.

## Longest Palindromic Substring:

The problem requires finding the longest palindromic substring in a string. The solution involves using dynamic programming or a Manacher’s algorithm.

## Regular Expression Matching:

The problem requires matching a string against a regular expression. The solution involves using dynamic programming.

## Maximum Subarray:

The problem requires finding the contiguous subarray with the maximum sum. The solution involves using Kadane’s algorithm.

## Valid Sudoku:

The problem requires checking if a given Sudoku board is valid. The solution involves using hash tables and nested loops.

## Implement Trie (Prefix Tree):

The problem requires implementing a Trie data structure. The solution involves using a class and a dictionary to store the Trie.

## Evaluate Reverse Polish Notation:

The problem requires evaluating a reverse Polish notation expression. The solution involves using a stack.

## Merge k Sorted Lists:

The problem requires merging k sorted linked lists into one sorted list. The solution involves using a heap and a merge process.

In conclusion, LeetCode provides an excellent resource for programmers to improve their problem-solving skills and prepare for technical interviews. The 20 most interesting LeetCode questions answered so far cover a broad range of topics and require various Intersection LeetCode.