# 解题思路:列举出所有合法的括号匹配,使用dfs.如果左括号的数量大于右括号的数量的话,就不能产生合法的括号匹配class Solution(object): def generateParenthesis(self, n): """ :type n: int :rtype: List[str] """ if n == 0: return [] res = [] self.recursion(n,n,'',res) return res def…

回溯法 百度百科:回溯法(探索与回溯法)是一种选优搜索法,按选优条件向前搜索,以达到目标.但当探索到某一步时,发现原先选择并不优或达不到目标,就退回一步又一次选择,这样的走不通就退回再走的技术为回溯法,而满足回溯条件的某个状态的点称为"回溯点". 在包括问题的全部解的解空间树中,依照深度优先搜索的策略,从根结点出发深度探索解空间树.当探索到某一结点时,要先推断该结点是否包括问题的解,假设包括,就从该结点出发继续探索下去,假设该结点不包括问题的解,则逐层向其祖先结点回溯.(事实上回溯法就…

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

Generate Parentheses: 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: [ "((()))", "(()())", "(())()", "()(())", &q…

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: "((()))", "(()())", "(())()", "()(())", "()()()" 在LeetCo…

题意 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: [ "((()))", "(()())", "(())()", "()(())", "()()()"] 输…

Description: 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: "((()))", "(()())", "(())()", "()(())", "()()()&…

[称号] 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: "((()))", "(()())", "(())()", "()(())", "()()()" [题…

题意: 产生n对合法括号的所有组合,用vector<string>返回. 思路: 递归和迭代都可以产生.复杂度都可以为O(2n*合法的括号组合数),即每次产生出的括号序列都保证是合法的. 方法都是差不多的,就是记录当前产生的串中含有左括号的个数cnt,如果出现右括号,就将cnt--.当长度为2*n的串的cnt为0时,就是答案了,如果当前cnt比剩下未填的位数要小,则可以继续装“(”,否则不能再装.如果当前cnt>0,那么就能继续装“)”与其前面的左括号匹配(无需要管匹配到谁,总之能匹配)…

# 解题思路: # 创建一个字典映射关系 dicts# 使用一个栈stk 遍历字符串s 得到一个新的字符串curItem 如果lastItem在dicts中的value和它相等 不做任何操作# 如果不等 入栈 有lastItem的 先append lastItem 然后是curItem ## 最后判断如果stk为空说明所给字符串匹配 return true class Solution(object): def isValid(self, s): """ :type s: s…

问题解法参考 它给出了这个问题的探讨. 超时的代码: 这个当n等于7时,已经要很长时间出结果了.这个算法的复杂度是O(n^2). #include<iostream> #include<vector> #include<stack> #include<map> using namespace std; bool isValid(string s) { map<char, char> smap; smap.insert(make_pair('(',…

# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 22: Generate Parentheseshttps://oj.leetcode.com/problems/generate-parentheses/ Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.For exa…

目录 题目链接 注意点 解法 小结 题目链接 Generate Parentheses - LeetCode 注意点 解法 解法一:递归.当left>right的时候返回(为了防止出现 )( ) class Solution { public: void recursion(int left,int right,string str,vector<string> &ret) { if(left > right) return; else if(left== 0&&a…

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…

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…

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: 有关P…

Generate Parentheses 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: "((()))", "(()())", "(())()", "()(())", "…

1. 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: The solution set must not contain duplicate quadruplets. Fo…

题目描述:Generate Parentheses 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: "((()))", "(()())", "(())()", "()(())",…

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]"…

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. Have you met this question in a real interview?     Example Given n = 3, a solution set is: "((()))", "(()())", "(())()",…

9.6 Implement an algorithm to print all valid (e.g., properly opened and closed) combinations of n-pairs of parentheses.EXAMPLEInput: 3Output: ((())), (()()), (())(), ()(()), ()()() LeetCode上的原题,请参见我之前的博客Generate Parentheses 生成括号. 解法一: class Solution…

leetcode 022. Generate Parentheses Concise recursive C++ solution class Solution { public: vector<string> generateParenthesis(int n) { vector<string> res; addingpar(res, "", n, 0); return res; } private: void addingpar(vector<stri…

Generate Parentheses Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]"…

Generate Parentheses 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: [ "((()))", "(()())", "(())()", "()(())", &qu…

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

leetcode-algorithms-22 Generate Parentheses 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: [ "((()))", "(()())", "(())()",…

Given a string containing just the characters'(',')','{','}','['and']', determine if the input string is valid. The brackets must close in the correct order,"()"and"()[]{}"are all valid but"(]"and"([)]"are not. 题意:给…

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: [ "((()))", "(()())", "(())()", "()(())", "()()()" ] AC…

一.题目说明 这个题目是22. Generate Parentheses,简单来说,输入一个数字n,输出n对匹配的小括号. 简单考虑了一下,n=0,输出"";n=1,输出"()":n=2,输出"()()","(())"... 二.我的解法 我考虑了一下,基本上2种思路,其1是暴力破解法,就是列出所有可能情况,然后判断哪些是匹配的. 汗颜的是,我没做出来.找到的答案: #include<iostream> #incl…