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https://leetcode.com/problems/find-original-array-from-doubled-array/ An integer array original is transformed into a doubled array changed by appending twice the value of every element in original, and then randomly shuffling the resulting array.Given an array changed, return original if changed is a doubled array. If changed is not a doubled array, return an empty array. The elements in origin..

[Problem]HintYou are given a list of bombs. The range of a bomb is defined as the area where its effect can be felt. This area is in the shape of a circle with the center as the location of the bomb.The bombs are represented by a 0-indexed 2D integer array bombs where bombs[i] = [xi, yi, ri]. xi and yi denote the X-coordinate and Y-coordinate of the location of the ith bomb, whereas ri denotes t..

[Problem]You start at the cell (rStart, cStart) of an rows x cols grid facing east. The northwest corner is at the first row and column in the grid, and the southeast corner is at the last row and column.You will walk in a clockwise spiral shape to visit every position in this grid. Whenever you move outside the grid's boundary, we continue our walk outside the grid (but may return to the grid b..

[Problem]You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money.Return the fewest number of coins that you need to make up that amount. If that amount of money cannot be made up by any combination of the coins, return -1.You may assume that you have an infinite number of each kind of coin. Example 1:Input: coi..

[Problem]You are climbing a staircase. It takes n steps to reach the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? Example 1:Input: n = 2Output: 2Explanation: There are two ways to climb to the top.1. 1 step + 1 step2. 2 stepsExample 2:Input: n = 3Output: 3Explanation: There are three ways to climb to the top.1. 1 step + 1 step + 1 step2. 1 ..

[Problem]You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.You may assume the two numbers do not contain any leading zero, except the number 0 itself. Example 1:Input: l1 = [2,4,3], l2 = [5,6,4]Output: [7,0,8]Explanation: ..