题目 Given a collection of integers that might contain duplicates, nums, return all possible subsets. Note: Elements in a subset must be in non-descending order. The solution set must not contain duplicate subsets. For example, If nums = [1,2,2], a sol…

题目 Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm? 分析 同LeetCode(274)H-Index第二个版本,给定引用数量序列为递增的:这就省略了我们的第一个排序步骤: O(n)的时间复杂度,遍历一次即可. AC代码 class Solution { public: int hIndex(vector<int>…

Medium! 题目描述: 给定一个可能包含重复元素的整数数组 nums,返回该数组所有可能的子集(幂集). 说明:解集不能包含重复的子集. 示例: 输入: [1,2,2] 输出: [ [2], [1], [1,2,2], [2,2], [1,2], [] ] 解题思路: 这道子集合之二是之前那道Subsets 子集合 的延伸,这次输入数组允许有重复项,其他条件都不变,只需要在之前那道题解法的基础上稍加改动便可以做出来,我们先来看非递归解法,拿题目中的例子[1 2 2]来分析,根据之前Subse…

题目 Follow up for N-Queens problem. Now, instead outputting board configurations, return the total number of distinct solutions. 分析 N皇后问题,同LeetCode 51 N-Queens,只不过,此题要求给出问题的合理解个数,而无需给出具体分布. 只需在上题的基础上,稍加修改,只计数便可达到要求,此题采用另一种求解N皇后问题的方法: 用一个一位数组来存放当前皇后的状态…

题目 Given a set of distinct integers, nums, return all possible subsets. Note: Elements in a subset must be in non-descending order. The solution set must not contain duplicate subsets. For example, If nums = [1,2,3], a solution is: [ [3], [1], [2], […

你是一个专业的小偷,计划偷窃沿街的房屋,每间房内都藏有一定的现金.这个地方所有的房屋都围成一圈,这意味着第一个房屋和最后一个房屋是紧挨着的.同时,相邻的房屋装有相互连通的防盗系统,如果两间相邻的房屋在同一晚上被小偷闯入,系统会自动报警. 给定一个代表每个房屋存放金额的非负整数数组,计算你在不触动警报装置的情况下,能够偷窃到的最高金额. 示例 1: 输入: [2,3,2] 输出: 3 解释: 你不能先偷窃 1 号房屋(金额 = 2),然后偷窃 3 号房屋(金额 = 2), 因为他们是相邻的. 示例…

题目 Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example, [1,1,2] have the following unique permutations: [1,1,2], [1,2,1], and [2,1,1]. 分析 用上一题的代码,完全可以AC,那是因为我们的库函数next_permutation()以及prev_…

题目 Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times).…

题目 Follow up for "Find Minimum in Rotated Sorted Array": What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 migh…

题目 Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 分析 本题目与上一题LeetCode(112) Path Sum虽然类型相同,但是需要在以前的基础上,多做处理一些: 与Path Sum相比,本题是求出路径,所以,在找到满足的路…