Given a string, find and return the longest palindromic substring in it. A palindrome is a word that reads the same forward and backward. The substring must be contiguous within the original string.
You are given an array of integers where each integer represents the height of a vertical line drawn on a 2D plane. The x-axis is represented by the index of the array, and each line’s height corresponds to the value at that index. Your task is to find two lines that, along with the x-axis, form a container that can hold the most water. The container’s area is determined by the distance between the lines and the height of the shorter line.
Given an integer array nums, find all unique triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0. The solution set must not contain duplicate triplets.
You are given an integer array nums and an integer target. Find three integers in nums such that the sum is closest to the target. Return the sum of those three integers.
You are given an array of integers nums and a target value. Your task is to find all unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that the sum of the four numbers equals the target value. The indices a, b, c, and d should be distinct.
