Given a collection of numbers that might contain duplicates, return all possible unique permutations.Example:

Given a collection of distinct integers, return all possible permutations.

Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.Each number in candidates may only be used once in the combination.Note:All numbers (including target) will be positive integers...

Given a set of candidate numbers (candidates) (without duplicates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.The same repeated number may be chosen from candidates unlimited number of times.Note:All numbers (including targe...

You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Note:You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.Example 1:

Note:All inputs will be in lowercase.The order of your output does not matter.

Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.(i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).

Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the order of O(log n).If the target is not found in the array, return [-1, -1].

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lowest possible order (ie, sorted in ascending order).The replacement must be in-place and use only constant extra m...

Given a linked list, swap every two adjacent nodes and return its head.You may not modify the values in the list's nodes, only nodes itself may be changed.

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Given a linked list, remove the n-th node from the end of list and return its head.

Given an array nums of n integers and an integer target, are there elements a, b, c, and d in nums such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target.

Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent.

Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

Given two binary trees, write a function to check if they are the same or not.

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.

Given a sorted linked list, delete all duplicates such that each element appear only once.

You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Compute and return the square root of x, where x is guaranteed to be a non-negative integer.

The input strings are both non-empty and contains only characters 1 or 0.

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Given a non-empty array of digits representing a non-negative integer, plus one to the integer.

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.

The count-and-say sequence is the sequence of integers with the first five terms as following:

Given an array nums and a value val, remove all instances of that value in-place and return the new length.