[题目] Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending o…

Given four lists A, B, C, D of integer values, compute how many tuples (i, j, k, l) there are such that A[i] + B[j] + C[k] + D[l] is zero. To make problem a bit easier, all A, B, C, D have same length of N where 0 ≤ N ≤ 500. All integers are in the r…

一.题目链接:https://leetcode.com/problems/4sum/ 二.题目大意: 给定一个数组A和一个目标值target,要求从数组A中找出4个数来使之构成一个4元祖,使得这四个数的和等于target,找出所有的四元组,当然这些四元组不能有重复的. 三.题解: 这道题实质就是3sum的变形,关于4sum问题,已经在https://www.cnblogs.com/wangkundentisy/p/9079622.html这里说过了,无外乎最外面两层循环,最里面的循环使用哈希表或…

题目链接 https://leetcode.com/problems/4sum/?tab=Description 找到数组中满足 a+b+c+d=0的所有组合,要求不重复. Basic idea is using subfunctions for 3sum and 2sum, and keeping throwing all impossible cases. O(n^3) time complexity, O(1) extra space complexity. 首先进行判断,由于是四个数相加…

Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: The solution set must not contain duplicate quadruplets. For exampl…

Given four lists A, B, C, D of integer values, compute how many tuples (i, j, k, l) there are such that A[i] + B[j] + C[k] + D[l] is zero. To make problem a bit easier, all A, B, C, D have same length of N where 0 ≤ N ≤ 500. All integers are in the r…

Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending order.…

整体思路同之前的一样,依然采取降低维度的方式进行 public List<List<Integer>> solution(int nums[], int target) { List<List<Integer>> result = new ArrayList<>(); if((nums.length<4)||(nums==null)) { return result; } Arrays.sort(nums); if ((4*nums[0]&…

4Sum Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending o…

Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: The solution set must not contain duplicate quadruplets. For exampl…

454. 4Sum II Add to List Description Submission Solutions Total Accepted: 8398 Total Submissions: 18801 Difficulty: Medium Contributors: Samuri Given four lists A, B, C, D of integer values, compute how many tuples (i, j, k, l) there are such that A[…

3sum: 1 class Solution { public: vector<vector<int>> threeSum(vector<int>& nums) { vector<vector<int>>result; vector<vector<int>>::iterator iter; vector<int>Middle; ; sort(nums.begin(),nums.end()); ;i<…

题目: Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending or…

题目描述:4Sum Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descend…

Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: The solution set must not contain duplicate quadruplets. For exampl…

Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. 解题思路一: 四路夹逼,C++: class Solution { public: vector<vector<int> > fou…

Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. 解题思路: 思路一: 使用DFS算法,JAVA实现如下: static String[] alpha = new String[] { " &q…

题目: 给定一个数组,找出其中和为0的所有4个数组合,每个组合内的4个数非递降. 解法: ①先排序,然后利用4个指针,前两个遍历,后两个在第二个指针之后的部分里夹逼,时间O(N3). ②或者利用一个哈希表先保存每两个数的和,然后类似于查找两个数的和等于给定值的过程. 代码: ① class Solution { public: vector<vector<int> > fourSum(vector<int> &num, int target) { vector&…

Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending order.…

问题描述: Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending…

Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending order.…

[题目] Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending o…

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. Note: The solution set must not contain dupli…

题目: Given four lists A, B, C, D of integer values, compute how many tuples (i, j, k, l) there are such that A[i] + B[j] + C[k] + D[l] is zero. To make problem a bit easier, all A, B, C, D have same length of N where 0 ≤ N ≤ 500. All integers are in t…

题目 给定一个包含 n 个整数的数组 nums 和一个目标值 target,判断 nums 中是否存在四个元素 a,b,c 和 d ,使得 a + b + c + d 的值与 target 相等?找出所有满足条件且不重复的四元组. 注意: 答案中不可以包含重复的四元组. 解题思路 将nums数组重新排列,然后从i = 0开始遍历,分别取j = i + 1.left = j + 1和right = nums.length - 1,将nums[i].nums[j].nums[left]和nums[r…

public List<String> letterCombinations(String digits) { LinkedList<String> ans = new LinkedList<String>(); if(digits == null || digits.length() == 0) return ans; String[] mapping = new String[] {"0", "1", "abc&qu…

题面 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. 给定无序数组,找到和为target的不重复的长度为4的子序列 样例 1. Given…

002* Median of Two Sorted Arrays There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)). class Solution: def findKth(self, A, A_start, B, B_st…

刷题备忘录,for bug-free leetcode 396. Rotate Function 题意: Given an array of integers A and let n to be its length. Assume Bk to be an array obtained by rotating the array A k positions clock-wise, we define a "rotation function" F on A as follow: F(k…

[leetcode]1. Two Sum两数之和 Two Pointers, HashMap Easy [leetcode]2. Add Two Numbers两数相加 Math, LinkedList Medium [leetcode]3. Longest Substring Without Repeating Characters无重复字母的最长子串 Sliding Window Medium [leetcode]4. Median of Two Sorted Arrays俩有序数组的中位数…