leetcode easy

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap […]

Given the root of a binary tree, determine if it is a valid binary search tree (BST). A valid BST is defined as follows: Input:

Two integer arrays, nums and multipliers, of sizes n and m, respectively, are provided to you, where n >= m.

The 3Sum problem is one of the most popular problems on LeetCode.It looks simple, but many developers struggle with it

Given a string s, return the longest palindromic substring in s. A string is called a palindrome string if the reverse of that string

Find the length of the longest substring without repeated characters given a string s. Example 1: Input: s = “abcabcbb”

You are given two non-empty linked lists that each represent a non-negative integer. The digits are kept in reverse order,

Provide the median of the two sorted arrays given two sorted arrays of sizes m and n, respectively. The entire

The Two Sum problem is one of the most popular beginner-friendly questions on LeetCode.It is frequently asked in coding interviews

Given the head of a linked list, return the node where the cycle begins. If there is no cycle, return null. There is a

Given the root of a binary tree, determine if it is a valid binary search tree (BST). A valid BST is defined as follows: Example

Given an array nums. We define a running sum of an array as runningSum[i] = sum(nums[0]…nums[i]). Return the running sum of nums. Example