题目:制造括号序列 难度:Medium 题目内容: Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. 翻译: 给定n对括号,写一个函数来生成所有格式正确的括号组合. For example, given n = 3, a solution set is: [ "((()))", "(()())", "…

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.    For example, given n = 3, a solution set is [ "((()))", "(()())", "(())()", "()(())", "()()()" ]思路…

Leetcode之回溯法专题-22. 括号生成(Generate Parentheses) 给出 n 代表生成括号的对数,请你写出一个函数,使其能够生成所有可能的并且有效的括号组合. 例如,给出 n = 3,生成结果为: [ "((()))", "(()())", "(())()", "()(())", "()()()"] 分析:给定一个n,生成所有可能的括号组合. 举个例子,n=3,需要生成三个括号,那最…

题目难度:Medium 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: The solution set must not contain duplicate quadrup…

题目: Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. 翻译: 给定一组整数,两个数字的返回索引,它们的和会等于一个特定…

题目:求所有全排列 难度:Medium 题目内容: Given a collection of distinct integers, return all possible permutations. 翻译:给定一组各不相同的整数,返回所有可能的排列. Example: Input: [1,2,3] Output: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ] 我的思路:每种情况中,每一个元素只出现一次,只是之间的顺序不同,那么…

题目: Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. 翻译: 给定一组整数,两个数字的返回索引,它们的和会等于一个特定…

22. 括号生成 22. Generate Parentheses 题目描述 给出 n 代表生成括号的对数,请你写出一个函数,使其能够生成所有可能的并且有效的括号组合. 例如,给出 n = 3,生成结果为: [ "((()))", "(()())", "(())()", "()(())", "()()()" ] LeetCode22. Generate Parentheses中等回溯算法 Java 实现 i…

题目:有效的括号序列 难度:Easy 题目内容: Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must…

题目难度:hard There are two sorted arrays nums1 and nums2 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)). Example 1: nums1 = [1, 3] nums2 = [2] The median is 2.0 Example 2: n…