qq_38904904的博客

问题：分析单向链表的优点是插入、删除操作方便，不需要移动大量的元素，缺点在于查找没有数组方便。并且本题需要从后往前逆序查找，单项链表很难实现。解决办法：翻转链表，从而变逆序查找为顺序查找！！！因此，本题的算法复杂度为两次翻转链表的时间复杂度，加上查找第n个结点的时间复杂度，由于翻转和查找都为线性时间复杂度，所以时间复杂度为O(n);/** * Definition for singl...

问题：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 o...

问题：Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.Example:Input: 1->2->4, 1->3->4Output: 1...

问题：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：从文件中读出每一行，将字符串中的标点符号替代为空格；使用字符串输入流将字符串里的各个单词赋给单个单词变量；将单词和出现的次数构成映射放入map中；排序: 复制map到vector中，重载>运算符进行排序。代码：#include<iostream>#include<map>#include<vector>#incude<al...

问题描述：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.The above elevation map is represented by ...

问题描述Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).Example:Input: S = “ADOBECODEBANC”, T = “ABC”Output: “BANC”Note:I...

leetcode 问题链接：(https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/)分析：此题需根据先序遍历和中许遍历的特点解决。对于给定的preorder和inorder序列，先序遍历每次取出的数可以作子树的根节点；而中序遍历时，该节点的左边肯定是它的左子树，右边点肯...

问题描述Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains only nodes with keys less thanthe node’s key.T...