Write a function to find the longest common prefix string amongst an array of strings. 解题思路: 老实遍历即可,注意边界条件: JAVA实现: static public String longestCommonPrefix(String[] strs) { if (strs.length == 0) return ""; for (int i = 0; i < strs[0].length(…

Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 解题思路一: 暴力枚举 共N^2量级个子串(从下标零开始),每次检查需一个for循环,等于是3重for循环,时间复杂度O(n^3) 解题思路二: 动态…

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest subst…

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list. Input: (2 -> 4 -> 3) + (5 -> 6 ->…

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: "((()))", "(()())", "(())()", "()(())", "()()()" 解题思路一:…

Implement regular expression matching with support for '.' and '*'. '.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). The function prototype should be…

Implement atoi to convert a string to an integer. Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases. Notes: It is intended for this problem to be spe…

Reverse digits of an integer. Example1: x = 123, return 321 Example2: x = -123, return -321 解题思路:将数字翻转并不难,可以转成String类型翻转,也可以逐位翻转,本题涉及到的主要是边界和溢出问题,使用Long或者BigInteger即可解决. 题目不难: JAVA实现如下: public class Solution { static public int reverse(int x) { if(x=…

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility) P A H N A P L S I I G Y I R And then read line by line: "PAHNAPLSII…

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)). 解题思路: 由于要求时间复杂度O(log (m+n))所以几乎可以肯定是递归和分治的思想. <算法导论>里有找两个数组第K小数的算法,时间复杂度为O(lo…

Given an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that…

  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. 解题思路: 新建一个ListNode进行存储即可,JAVA实现如下: static public ListNode mergeTwoLists(ListNode l1, ListNode l2) { ListNo…

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 a linked list, remove the nth node from the end of list and return its head. For example, Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, the linked list becomes 1->2->3->5. Note: Given…

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…

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…

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero. Note: Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c) The solut…

Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 解题思路: 类似上题,方法多多,本题直接给出上题中字典匹配的代码: JAVA实现: static public int romanToInt(String s) { int num=0; String Roman[][] = { {"", "I", &q…

Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. 本题思路比较简单,难度主要集中在罗马数字本身,直接贴代码. 思路一,从高位开始: JAVA: static public String intToRoman(int number) { int[] values = { 1000, 900, 500, 400, 100, 90, 50…

Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a containe…

Determine whether an integer is a palindrome. Do this without extra space. 解题思路一: 双指针法,逐位判断 Java代码如下: static public boolean isPalindrome(int x) { if (x < 0) return false; int temp = x,beginIndex = 0, endIndex = 0; while (temp >= 10) { temp /= 10; en…

public class Solution { public String longestCommonPrefix(String[] strs) { if(strs == null || strs.length == 0) return ""; String pre = strs[0]; int i = 1; while(i < strs.length){ while(strs[i].indexOf(pre) != 0) pre = pre.substring(0,pre.len…

Write a function to find the longest common prefix string amongst an array of strings. 题解: 简单的暴力遍历解决 class Solution { public: string longestCommonPrefix(vector<string>& strs) { int n = strs.size(); || strs[].empty()) return ""; string…

小二好久没有更新博客了,真是罪过,最近在看linux的东西导致进度耽搁了,所以今晚睡觉前怒刷一题! 问题描述: Write a function to find the longest common prefix string amongst an array of strings. 解题思路: 该问题就是找到所有数组字符串里面的最长相同前字串.所以我的思路是先找到数组中最短的那个字符串,然后每次比较的时候最多循环该长度就行,这样避免字符串下标溢出的问题.设置StringBuilder对象用于存…

Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string "". Example 1: Input: ["flower","flow","flight"] Output: "fl" Exa…

所有字符串的公共前缀最长字符串 特点:(1)公共所有字符串前缀 (好像跟没说一样...) (2)在字典树中特点:任意从根节点触发遇见第一个分支为止的字符集合即为目标串 参考问题:https://leetcode.com/problems/longest-common-prefix/description/ Write a function to find the longest common prefix string amongst an array of strings. If there…

problem: Write a function to find the longest common prefix string amongst an array of strings. 寻找 0 ~n 个字符串的最长公共前缀 thinking: (1)公共前缀非常好理解.按位匹配就可以 (2)非常easy忘记处理0.1个字符串的情况. code: string prefix(string &str1, string &str2) { string tmp; int i=0; whil…

Write a function to find the longest common prefix string amongst an array of strings. public class Solution { public String longestCommonPrefix(String[] strs) { if (strs == null || strs.length == 0) { return ""; } else if (strs.length < 2) {…

14. Longest Common Prefix Total Accepted: 112204 Total Submissions: 385070 Difficulty: Easy Write a function to find the longest common prefix string amongst an array of strings. 思路: 题目很简单,求字符串数组的最长的共同前缀.也没什么思路,诸位比较呗,代码如下: public class No_014 { publi…