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], [1,2…

[题目] Given a set of distinct integers, nums, return all possible subsets (the power set). Note: The solution set must not contain duplicate subsets. 求子集,无重复数 [思路] 1.有回溯法模板 2.将tmp加入进ans.tmp用来存放第i个元素的子集.回溯产生第i个元素与其后[i+1,len]元素产生的子集(i-1前已经产生过,不重复遍历).因第i…

78. Subsets 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]…

Trapping Rain Water Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining. For example,  Given [0,1,0,2,1,0,1,3,2,1,2,1], return 6. The above elevation ma…

Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For example: Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20 / \ 15 7 return its…

Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. For "(()", the longest valid parentheses substring is "()", which has length = 2. Another example is &…

LeetCode 78 网上已经又很多解这题的博客了,在这只是我自己的解题思路和自己的代码: 先贴上原题: 我的思路: 我做题的喜欢在本子或别处做写几个示例,以此来总结规律:下图就是我从空数组到数组长度为4的示例 在写这些例子的时候,我发现,数组中每增加一个元素,其结果就是前一个结果集(数组长度为n-1的结果)的基础上加上新增的这个元素得到的结果集再加前一个结果集:可能叙述的不清楚我把上面的图片规整下把 例: 规律差不多讲完了,如果还是不清楚请留言,我们一对一解释,现在来贴代码 结果:…

There are N gas stations along a circular route, where the amount of gas at station i is gas[i]. You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to its next station (i+1). You begin the journey with an e…

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution. For example, given array S = {-1 2…

第一题是输入数组的数值不相同,第二题是输入数组的数值有相同的值,第二题在第一题的基础上需要过滤掉那些相同的数值. level代表的是需要进行选择的数值的位置. 78. Subsets 错误解法: class Solution { public: vector<vector<int>> subsets(vector<int>& nums) { vector<vector<int> > result; if(nums.empty()) ret…